If you pass a whole raw disk, not virtualized, then TrueNAS should not complain. I don’t know if you can do that in proxmox, I haven’t tried.
Personally I’d get rid of TrueNAS. Even if docker is down, the VM with the data is still up and accessible over anything running on the VM, like scp via ssh.
Same way as I do on Linux. There was a post a few weeks back about an Arch update breaking vlc if you don’t manually install a new optional dependency after an update split the package.