There’s few apps I can think of that fail when the service restarts. At worst Jellyfin and Home Asssistant take a minute or so to be available again. The former usually does not pose a problem because of client side caching while streaming. HA would be quite annoying, altough lights etc would keep their current state so it’s unlikely I’d even notice.

That said I don’t use unattended upgrades.

Yeah, especially after discovering microvm.nix [1] I’m tempted to switch from Proxmox to NixOS.

Edit: The VMs/LXCs are declared with Nix anyway.

[1] https://github.com/astro/microvm.nix