Some people seem to hate on it, but I love Docker, it works well for what it has to do and has relatively low overhead as far as I can tell. I personally virtualize a Debian server on Proxmox for my containers just so as to keep everything even more compartmentalized, but it takes more work than it’s worth to set up.
And if you don’t like Docker for whatever reason, you can also try Podman which is API compatible with Docker for the most part.
there are lots of cheap domain registrar options but if you’re looking for a cheap .com I always go for cloudflare, they also offer .org for pretty cheap and many other options as well. The domains other than the common ones are pretty decently priced as well. I migrated all my domains there last year and it’s really simple, integrates with their DNS really well and payment is pretty streamlined.