You’ve all heard the saying that “the best camera to have is the one that you have at the time”. Even if said camera is the one with your cell phone. Having said that:

I, too, have seen, and have taken, photographs with my iPhone 7 that are difficult for the average person to tell that it was by the cell phone camera and not the DSLR. Of course, I have NOT tired enlarging any images to 8x10 or larger, so I really don’t know how well they would do. But, for the most part, for viewing on the computer, e-mailing or posing on “social media”, the cell phones do a decent job.

With my iPhone 7, I’ve made videos, both during the daytime AND at night, that rival or even surpass those made with my Nikon D7100. Now, there’s a good chance that I don’t have the settings on the D7100 correctly set up for doing video, but the iPhone just “does it” and it’s always a good result.

There seems to be an implied “Perhaps...” intended.

Alas, that’s a problem with living in a world wide forum. Colloquial, regional, and cultural usages vary. People who seem to be making mistakes are just speaking and writing what they grew up with. It’s correct FOR THEM in their native environments.

I learned “proper” American English from Harbrace 6th Edition Handbook. My wife learned from 7th. We quibble over language often, but heck, they’re up to version 13 now.

As long as I can understand it, I don’t care.

It is very possible that you could do very well with your Sony but why not take something like the MFT with lenses for a trip that could easily be the trip of a lifetime. I say the same about the full frame.
You seem to be learning your new Sony camera and that is not the way to travel with a new camera. You know your MFT and your full frame cameras better so shooting should be much easier with something you already know.
If I were traveling to Iceland for sure I would take one of my cameras with interchangeable lenses along with my tripod. You could regret not doing so.

I have been looking at older 28-70 F2.8 lenses on eBay. Quite a few of them are being sold As-Is due to non functional AF. Plus many also describe “squeaky “ AF which is indicative of soon to fail AF. This lens was the precursor of the 24-70 F2.8 in Nikons “Holy Trinity” and as such was one of the high end lenses. Most on here seem to be using consumer or entry level lenses though and quite a few of them on eBay seem to be “as-is”. Not like the older manual focus lines, many of which are still delivering.