Pretty much the only time I hear the M1 fans are when I'm doing something with tensorflow-metal, ffmpeg'ing or rendering video, or otherwise deliberately thrashing the CPU. e.g. Minecraft (albeit modded with Sodium et al) makes it noticeably warm but no fans.
I’ve had an M1 mini for a year now. I think it has a fan, but I’ve literally never heard it, even though it sits right in front of me. Even when using all cores to do video encoding.
The Mac Studio actually has a low RPM always-on fan. It's quiet enough that it can get away with that, and not turning it on and off avoids the noticeable transitions in volume. Under very heavy load the fan speeds up slightly.