I have a used Lenovo Thinkcentre mini with an i3-7100T and 16gb RAM. I have Ubuntu server LTS installed on it and I run everything in docker containers.
I host:
- jellyfin server for my friends and family
- qbittorrent to download for the JF server(behind a VPN)
- Jellyseerr for requests
- Jackett, Sonarr, and Radarr for downloads
- a Minecraft server
Using a Pixel 5a, running CalyxOS. No problems with the phone and no plans to upgrade any time soon.