OP, listen to this person. Docker will earn you cash. Podman is nicer to work with for your own shit.

You’re usually stuck with what your seedbox provider gives you.

No. Plenty of places pay devs well. Top end jobs are mostly in the US. There are plenty of well paying jobs elsewhere.

I’ve done the same thing as the person you replied to is suggesting for around 10 years now. It works very well for a home user because parts etc are readily available. Most hypervisors will run on x86/amd64 hardware without issue. Check out something other than proxmox. LXC is one suggestion. If you’re going to stick with Debian look into SAMBA with BIND to ensure ease of sharing and cross platform integration.

Another reason to not get an old server is power, noise and thermals. They’re designed to live in an air conditioned room. Anyone who works in server rooms for any length of time will tell you to wear ear protection.