Yeah you could try installing Linux with the Windows drive disconnected. I had Windows and OpenSUSE Tumbleweed installed with two drives on my old PC without any issues.
Yeah I have the flip 6. I upgraded from the flip 3 for a larger cover screen. No issues with either of them.
I like that it takes up less pocket space and most tasks can be done on the cover without opening the phone. The flipping is neat but honestly I'd rather have a modern 4-4.5 inch android slab. Too bad all the major phone manufacturers have switched to only making giant pocket tablets.
I really enjoy Tumbleweed. I've been using it for about 18 months now without issue. One thing to note though is that TW only packages production release Nvidia drivers. This means you will not have the 555 or 560 drivers that make Wayland usable by default. You can always install the latest drivers with the run file provided by Nvidia. Some people also use the CUDA repo to get the newer drivers. However, I'd think both of these options may be the type of tinkering you are trying to avoid.
Overall I think TW is a great distro but it may be a bit more setup for Nvidia gaming on Wayland than you are looking for. If you're down with doing a little tinkering or gaming on X give it a shot. You can always roll back if something gets messed up.
I really liked sony back when they made the compact series. ZX1 compact was my favorite smartphone but sadly it stopped working on my carrier. Now I'm using a galaxy zflip. The size when folded feels nice in my pocket. Closest thing I could find to a "small" full featured android.
Endeavor is a also a very good choice. It is pretty much arch with some QoL stuff added. Uses the arch repos for packages.