The M1 mini would be a great home server in its form-factor (small size), power usage and performance. As the current mini is pretty much an empty shell, the minis' size should get smaller in the next generations. Intel nucs are popular for these reasons, but it seems the M1 will give better performance/power/size.
I've used Linux for the past 20 years. I recently tried OpenBSD because I never used a BSD, so I thought I wanted to have a look and had a pet project building a home router. My experience of OpenBSD as a headless server is it's been an absolute joy to use. Simple, well structured and strong consistency with config and where files are placed, great man pages etc. From no experience at all with OpenBSD I had a fully functioning router with PF, multiple vlans, cross vlan firewall roules, mdns repeating etc etc within a few hours. Regarding fiddling with things, for a headless server, it's been the easiest server I've set up to date.
The only negative experience I've had is when not shut down properly I've had a few issues starting it. I think I could solve that if I wanted to. Using it as a router I can set up a read-only filesystem etc. The other drawback is it's not Linux and I use Docker daily for development so would need to do what Docker on OSX does and run Docker in a Linux vm.