Hey there @tolkien30000!
For the most part you won’t have any issues with assets. Nanite assets can be converted to normal SMs in their details in editor. There are some plugins, and some lesser features that aren’t available either, but in most cases I wouldn’t worry too much here.
Most systems will work for M1 macs, but two key systems do not. Nanite does not work at all for M1 macs due to 64 bit atomics, and Lumen causes some artifacting from reports I’ve seen. This thread has some users discussing compatabilities with Lumen and Nanite (long read though) and even a user that almost got Nanite working on M1 macs.
You should be able to produce a AA quality FPS on your M1 just be wary to test builds often, and issues that arise during packaging, especially those that stem from Xcode issues can be hard to diagnose in larger projects.
Not at all! Nanite is exceptionally good at keeping performance for high poly geometry, but for many game ready assets, it’s entirely unnecessary and won’t provide a massive performance boost. For example, one project I’m on currently has absolutely no nanite geometry, because swapping over for low to mid poly assets provides little or no gains. Lumen is amazing at making nice lighting utilizing GI and emissives, but it’s by no means required for a game to look good.
Overall, I know many developers that even prefer to work from Macs, many older than your M1. Mac support is getting better over time as well, while some features aren’t able to be backported due to some constraints, the goal in the future was to have as much parity between OS’s as possible.