I think Debian Server + Docker compose. Its the easiest way to get started and has the most documentation for. To me, the OS itself is the least concern - just get something maintainable. Then choose services you want from selfh.st/apps/ and have a go with them. Most services give you docker compose scripts so that is by far the easiest way.

If there are two of you with accounts, then I would suggest these:

• Reverse proxy (caddy, nginx, etc)
• SSO authentication (authentik, authelia etc)
• VPN for access (wireguard, netbird, tailscale etc)
• Security (fail2ban, crowdsec, etc)

On top of Home assistant and the Jellyfin / arr stack you mention, I would recommend Immich (google photos), Paperless NGX (letter scanning / management), Vaultwarden (password manager), FMD (find my device server for android phones), and SearNGX (private search engine).

Potential alternatives would be NixOS (fully scripted) and Proxmox (better containerisation but still got to decide what you install on each container, such as Debian + docker). You could also use podman instead of docker compose, which is more secure but a bit more effort to adapt to. However, if access is only through the VPN and you have two users, Debian + docker would be fine.