I’ve been hosting services for myself and others for over 25 years now: starting on IIS6, moving to Windows Server, eventually to Debian, and now to an entirely dockerized stack. Self-hosting allows me to control my destiny in a way that using cloud services run by others doesn’t. If an update causes screenreader issues, I can just not apply it. If I don’t like the default themes, I can change them.
It pretty much depends on Debian. You could also run cosmos itself in a docker if you wanted.