As the subject says.
Asking more out of curiosity than anything - I don't actually plan to attempt such an upgrade. I'm still running OMV5 on Debian Buster and it's been performing admirably. I don't feel the need to upgrade yet, but once I do, I will start fresh with a clean install of OMV7 and reconfigure everything to my needs.
Also, it's nice to see the forums are alive and well after a few years of me not hanging around here, and so is OMV.