Given the RAM in an M1 machine can never be upgraded, I wouldn't even think about less than 64GB. More RAM is always helpful; if not now, then in the future. And probably now, too.
If you use Resolve's Fusion page, or might in future, you'll want as much RAM as possible. And even if Resolve never needs it for what you use it for, more RAM means you can run multiple programs at once without needing to think about closing them down. Photoshop, Lightroom, Blender, Logic Pro, etc, etc. And even if you don't use those sort of programs, you're still likely to want a web browser with tabs, Preview, Mail, etc. It all adds up.
On top of that, any RAM you're not using can be used automatically by the OS as filesystem cache, speeding up access to files on disk - including Resolve's cache.
Here's a look at my current RAM usage:
I have Resolve open using about 10GB, and Fusion studio using 6.3GB. But my total RAM usage is 43GB, on account of also having Firefox, a PDF viewer (for various manuals), Path Finder, email client, etc. And then I have 32GB of filesystem cache - most of which is Resolve's render cache. So my Resolve cache on disk is also being cached in RAM - meaning that when I play back my cached timeline clips, it's effectively like I have a RAM cache.
I know not everyone wants or needs to run so many programs. But IMHO more RAM generally means better performance, more flexibility, and less chance of running into problems in future years. Especially for a system where RAM can never be upgraded.
When I bought 128GB RAM for this system I bought 4 x 32GB sticks instead of 8 x 16GB, so I would have the option to easily upgrade to 256GB RAM in future. Just in case I might ever need that much