You can get both Bambu and Orca skicer(s) from the AUR if your distro is arch-based or a flatpack of either if you’re Debian based if that’s your main concern, but from what you’re saying you’re more interested in the “open-ness” of the platform. I’ve never owned a Prusa myself, but I’ve seen them in action and was very impressed. I currently run a P1S and daily-drive Debian now and couldn’t be happier, but iI do understand the concerns people have with Banbu. Sounds like you’ve done your research, and if the Prusa ticks all (or the majority) of your boxes, is local to you and you don’t mind the price tag, I don’t think you’d be disappointed at all.
Can’t recommend a filament dryer enough, this is a great tip. The AMS itself helps keep your filament more dry longer than being exposed to the elements, but you really should consider a good dryer.
As far as nozzles go, mind the filaments you plan to use with them, as a .2 nozzle is way more likely to clog with “filled” filaments, but if you’re printing non abrasive, non filled filaments and you want the extra detail you can’t beat a .2 - i purchased the CMYK lithophane kit and the detail with the smaller nozzle makes them almost photo quality. The great part is, though, bambu nozzles are far simpler to change than most other printers. If you plan on swapping them often, I’d recommend printing the cable/connector removal tools as the connectors can be a bit fiddly.