I've been running HAOS under ProxMox for almost a year now (just looked and it's a year in 2 weeks time).
I've had 0 issues with it in that time, and it's been way more stable than before on a PI4 - although I'd suspect a PI5 with NVMe would perform just as good - SD card's aren't fast enough for HA.
As for setting it up, I just restarted it from scratch rather than copy everything as is from the older setup.