I have both, but use the 20 F1.8 due to its light gathering and shorter shutter speed to avoid star trail.
However, if composition requires a wider FOV and star trail is not an issue, then I use the 14-30.

I have a 200-500 lens to use for BIF, after I cannot carry the 500 F4. Then I got the 500 PF then the 200-500 stays home most of the time. It is about 60% of the weight and shorter so easily hand holding. Of course I lost the zoom capability, but I love close up picture so that is my trade off.
I used on the D7200, Z6 and Z7 (mostly on DX mode, but some time on FX too if I am too close) :-))

I went there in late Dec 2016. and also took the helicopter ride. Very well worth it, about $165/ride/person. Our group took the whole helicopter. I was fortunate to sit right next to the pilot as they saw me carry 2 cameras D800 with 24-70 and another D7200 with the 80-400. My seat floor is glass so I can shoot on all directions. A very well worth ride for 20+minutes. We also walk along the falls on the Zimbabwe side to take photos. It is low water season but still plenty to enjoy and you can actually see the cliffs and the canyon bottom. On the high water season, there are so much mist that you can hardly see the bottom and the whole cliff structure. I use my 400mm to shoot folks dipping on water holes on the Zambian side. Our hotel (African safari style) is right next to the high pricee British Victorian style resort hotel, and we can walk to downtown for eating and shopping.
Here is my album:

https://flic.kr/s/aHskPydqDn

I have used DXO long time ago from the Optics Pro version to the current PL4. Prior to that I use Capture NX-2 and Nikon discontinued it, forcing me to change to different raw processor and post editing. As I am a Nikon photographer, not an artist (no pun intended), I found DXO is easier to maneuver than Photoshop and the price is reasonable, before Adobe subscription model. I have no problems about camera body and lens profile as I am mostly Nikon. PL4 is my current main raw processor and editing.
BUT, I used Photoshop for multi-raw image processing, like panorama and stacking, as PL4 has no such functions. So be aware.

I have had many CD and DVD failed in the past. I also had few Hard Disk Drive failures too. No archiving media is completely fool proof. If you want to increase your survival chance, you would have to have redundant copies. I have the same copy on both the CD/DVD media and HDD. On the HDDs, I have 2 exact copies, one at my house and the other at my daughter house.

I have been in Tanzania safari last February 2020. I use my Lowepro 200 AW (all weather) and keep my unused lens in ziplock bag fine. I even bring small clear garbage bag (5 gallons size) for use if necessary. I used cheap OpTech clear vinyl camera cover with draw string at the lens end ($7 for 2). As the environment is very dusty, it is not advisable to change lens during the day (even in the evening if you stay in tent lodging). Even tough I have a special lens changing bag, I did not use as my body is quite dusty during the day shoot.
I am fortunate not having a torrential rain during my 8 days there, just a few sprinkles.
Hope that will help.

I shoot video on Nikon Z6 and my wife shoots on iPhone 11. We both set to 4K 30P. Generally, we got the same video and quality. However, my wife complains about 3 things: (1) No control of Depth of Field, (2) IQ is bad when in low light scenes, and (3) zooming is limited.

Beside the extra ticket for the camera, you may also need to pay extra ticket for the tripod or monopod, if allowed.
I was in Egypt and Jordan twice in the last 4 years, brought with me the Nikon D800 and the versatile 28-300. So I am ready for the shoot anytime as the tour moves fast, and no change in lens (windy, dusty and sweaty). Mostly in the 28-100 focal length, but some nice 200-300 for far away detail and background compression. If I need more than 28mm, then I shoot pano hand held.
If you have a GoPro or similar, great to bring along for camel ride and river cruise action.
Enjoy.

AF-P lenses use a “Pulse” motor or “Stepping” autofocus motor and are even quieter and smoother to autofocus than an AF-S lens.
Like you said, PF lenses are the phase fresnel lenses.
They are two different technologies applied to 2 different areas of a lens design.
Hope that will help.

Yes, it is a Nikon lens. I have the FX version, not the DX version. Light and cheap too.

I have both. And both serve me well. It bogs down to the environment you are shooting. For example, Africa Safari is vast and most animals are far away. So the 200-500 is better. For Ecuador Galapagos, animals are both close and far, so the 80-400 is better suited. If you can afford both, put one on each camera.
Or for a lighter weight, I use the 70-300 PF lens on one of the camera.
Since getting the 70-300, I am using it more and more and the 80-400 stays home as I always go out with 2 cameras.

You already have the best equipment (D5 and D500) for BIF and wildlife action in the Nikon world. The Z6 camera has better video capabilities but lesser capability in sports and wildlife than the equipment you already owned. For landscape, portrait and general photography, Z7 is barely better than D850 in terms of AF precision and capability due to focus peaking, zooming view, etc.
What you gain in mirror less is (1) size and weight, (2) see your final image before taking the shot via EVF (WYSIWYG) since what you see reflects all your camera settings, (3) no mirror slap to worry, (4) IBIS (sensor based image stabilization and (5) virtually no more or much less AF tuning in DSLR.

I hope this short summary will help you.

If you can afford the cost and the wait (due to back order and limited supply on hand), the Nikon 500mm F5.6 PF prime is the best in IQ, weight (2 lbs lighter than the 200-500) and compact (about less than 2/3 of the 200-500), albeit almost 3 times the cost at $3600. It is very much hand hold-able.

The electronic view finder of my Nikon Z6 and Z7 is 2-3 times more resolution than my rear LCD. It is also brighter and "optically" better due to the glass in front of the EVF. No glare during broad day light viewing.

I have been in both South Africa and Tanzania. In South Africa, I was at a private lodge in a private game reserves commissioned from Krugers National Park. In this space, we do game drive very early in the morning, leaving at 6am when it was still dark until 9:00am, rest during the day, and then start the late afternoon game drive at 6:pm (dusk) until close to 9:PM. We saw lot of hunting and kill by lions. Yes, the guide is on control of game drive and rule. But there is always some unruly folks who disobey advises and rules. One vehicles are charged by the two largest males of the group of 50+ elephants due to the standing up and yelling of the occupants. Our vehicle is stopped and stuck right in the middle of the group passing by, being there about 50 feet from the first group of elephants, but then was surrounded by the moving remaining part of the group. We sat still and quiet as instructed by the driver/guide. I do not know we are lucky or just be safe by playing by the rules. I was there for 3 days, 6 game drives in total.
In Tanzania, it is quite different. We are limited by the sunrise and sunset rule, even though we stayed at tented camps right in the middle of Serengeti. Our vehicle had a special limited off road pass, but our driver/guide is very senior by watching him direct and advice other junior drivers. Experience showed through the age and seniority, and some respect was given to those driver/guides wearing company uniform like ours.
Our driver rarely goes to places where a lot of other vehicles converged, always on the radio to know what is going on and communicate with other experienced drivers.