To setup proxmox, you could install it on top of your current debian install : https://pve.proxmox.com/wiki/Install_Proxmox_VE_on_Debian_11_Bullseye
Docker in a lxc container is also used quite a lot with proxmox and would allow you to keep some resources without allocating everything for a docker VM.
I would start by moving the services running on the host to a VM, less downtime for those when switching to proxmox.
Also, if possible, address the data issue before migrating. If you can add more disks, you could setup a new zfs pool, ready to be used by proxmox.
And don't forget to backup (to external storage), you never know what could go wrong.
Great post, thanks for sharing 👍
I would suggest to give Ansible a try, it would make it really easy to deploy a new service with all required users and config.
The bitwarden client caches the database locally, so you can still access your credentials even if your server is down.