The migration is bound to happen in the next few months, and I can't recommend moving to incus yet since it's not in stable/LTS repositories for Debian/Ubuntu, and I really don't want to encourage adding third-party repositories to the mix - they are already widespread in the setup I inherited (new gig), and part of a major clusterfuck that is upgrade management (or the lack of). I really want to standardize on official distro repositories. On the other hand the current LXD packages are provided by snap (...) so that would still be an improvement, I guess.
Management is already sold to the idea of Proxmox (not by me), so I think I'll take the path of least resistance. I've had mostly good experiences with it in the past, even if I found their custom kernels a bit strange to start with... do you have any links/info about the way in which Proxmox kernels/packages differ from Debian stable? I'd still like to put a word of caution about that.