If you want to move to Proxmox then I say give it a go.
Maybe just keep what you have running and set up another machine to have a play. If you like it, then stick it on your main machine and work out how to replace everything, could be a fun project for you.
I use Proxmox and have Open Media Vault as my NAS. I use SMB/CIFS to share the drives and have a share that Proxmox can use for daily backups, as well as having backups on the main SSD every week. I need to off-site backups but I haven’t researched that yet.
I have a Debian VM that runs Docker and have everything running on that except OMV and Home Assistant. I have another Debian VM that I spin up to try things out.
RAM-wise I’m hitting about 12gb so if you have something with 16 lying around you can easily try out most of what you have running already, and if you don’t have anything to run it on you’re talking under £100 for a mini PC.
Give it a go, I’m sure you can come up with something to run on a mini pc anyway