What ever lens is smaller and lighter. You want to stay as inconspicuous as possible.
I used to carry mine at belly button level against me and just turn and shoot. Sorta like the camera was taped to me, I would carry it that close.
You may also want to consider the very, nice, very compact, very inconspicuous Sony 20 mm 1.8 lens. It get excellent reviews and is very sharp.
But, I have to tell you, if I find someone who really impresses me, I go out of my way and ask to take their image.
But most of the time I just really look for a good shot while carrying my 70-200, this lens gives you a DISTANCE from folks, so they do not feel their personal space invaded and most of the time I go unnoticed, especially at 200mm.
Below is an example of this type of street photography, by the way, it is referred to street photography because your the one in the street. And your images do not always have to include people to be effective.

Wood Storks can carry large and heavy loads due to their large 66 inch wing spans. Which makes that branch it is carrying at least that long or even longer.
Exposure on birds in flight are manual and based on a meter reading of green grass or tree foliage, I then usually stop down 2 stops for a white bird. If I had shot in Auto, my meter would have read the sky and stopped down so far the Wood Stork would have been too dark.
Wakodahatchee Wetlands.

Midwestphoto.com

I was a professional photographer for over 45 years. In retirement we live in Florida 6 months. I take wildlife images and post them on facebook for my northern friends. I am a top contributor to the Wakodahatchee website and I post here daily.
When my wife and I come to Florida in November my northern folks start asking for images.
I also run a free photo tour business. Well, I guess because it's non profit I can't really call it a business, I guess I will call it a hobby.
I also have a gallery at the Gatehouse Winery in Jamestown Pennsylvania that takes up most of my summers.
Good luck and keep on shooting until the end.

Please use the "quote reply" so we know with whom you are talking about. Thanks.

Still, for about 6 months we live on the border of Pennsylvania and Ohio on Pymatuning Lake. I also post on facebook for my folks up north. In fact, once we drive down in November, my folks up north know it and start complaining they do not have any images to look at during morning coffee.
November here is a down month for birds in general, so I have saved up images from past years I will start posting with them in an effort to stop the bombardment of complaints.

I would have to estimate that I was about 50-75 yards from the Heron. As I was waiting for a a different Heron to bring sticks to it's nest I noticed this guy yawning several times. So I just elevated my lens and waited for him to do it several more times, this one came out the best.
I usually stop in certain spots where I know the birds are active, I also have my manual exposure pre set for both birds in flight and on the ground which are basically the same because the sun is lighting them both the same.
Good luck and keep on shooting until the end.

Most are made with very thin metal, some were made with fine cloth. Cleaning these are not for amateurs.

Nikon vertical grips are better made, will sell for much more than off brands, and were specifically made for the D850. I enjoyed mine for years.
You can get them off ebay for as little as $58.70 or best offer. Do not compromise on your expensive D850, always ride with the brand.
https://www.ebay.com/itm/145680745780?itmmeta=01HSJZBBFZZ4Q5B48XPZ7Y93P2&hash=item21eb3fc534:g:H0kAAOSwERxl~HTE&itmprp=enc%3AAQAJAAAA8NqbEE6Ot2djHMrWVOj1jugRbdacVEK2JeJ2w4NKAKpQjRNnDltNrE6DOKej8VA4VqYdgNsh8sAayqFUVoOpuYTSErb7ai7eHIYJPmzppmd5zy4xIdGIENt1GPIVC%2BrMCRF%2FDclIkjoG7S3BDD%2BSVyag2llmQ3oFmQ%2B6OKrA0QnENpoVHukd4LZPycOUTa0NrfzX70ucIdkVeNLah5Ep1pjGiBtQo%2BX4ZwnhWPCkQvIP%2FD%2BkS9Cx4c3Fkp3TLGv%2BS2qo1lpRe43%2BJtTYigglp%2FbVaqlboOJXNPC7AnloZFQpL2RuKv6RdO%2B3p9%2FCcX%2BqvA%3D%3D%7Ctkp%3ABk9SR4i4rd_MYw

Both will deliver sharp images. Honestly, image quality with todays lenses come down to the photographers knowledge and skill rather than judging the overall all image quality of a particular lens.

Tiffen makes good ones, and B&H offers K&F filters, they are inexpensive and work well, you should check them out.
https://www.bhphotovideo.com/c/search?q=72mm%20ND%20filters&sts=ma

K&F are also featured on Amazon
https://www.amazon.com/s?k=72mm+nd+filter&crid=2OQ4SHO6SQZ3C&sprefix=72+mm+ND+filter%2Caps%2C142&ref=nb_sb_ss_ts-doa-p_1_15

To be honest I have also bought ND filters from Amazon and have been more than pleased. Contrary to popular belief inexpensive ND filters for amateurs work very well and should be considered.
The image below was shot with a good, inexpensive K&F ND filter.

Moment of capture. A Tri-colored Heron captures a minnow. Wakodahatchee Wetlands

Exposure info: Sony a1, Sony 600mm f4 @f4, 1/2000 sec. iso 2000.
In this action sequence I shoot at 30 fps RAW to get that "moment of capture". I always recommend my clients to shoot at the top of their fps on their camera's. You only need a second or so. Yes, you do end up with toss outs, but your chances of getting that "moment of capture" increases. It also helps to know how Tri-colored Herons hunt, then you can better anticipate when to open the shutter.
I also choose to shoot at 1/2000 sec. to get those frozen water drops. It would also aide me if I see a bird in flight going by a few seconds earlier or later. Wing tips can be frozen at 1/4000 sec.
Good luck and keep on shooting until the end.

The light just after sunrise and at sun down are about 5-7 stops from a noon exposure. How is one exposure settings valid for that spread.

So, dark sky's, early morning, cloudy skies, bright sun, late on the afternoon, rain, your magic exposure is 1/2000 sec. f8 @ iso 400.