Technically OMV is not an OS, OMV is software that runs on top of an OS. It provides a GUI front on some services, makes things easier to install/configure via that GUI, etc. The underlying version of Debian, is the actual OS.
No, OMV 6 will not work on Debian 12. If you read the tags on your thread, OMV 7 is tagged "RC1".. That's Release Candidate 1. While it is basically stable, it is technically not the stable release yet. OMV 6 is the current stable release. However, as mentioned.. OMV 7 is bound to convert to stable any time now (I've used it about 3mo w/o issue).. Debian 11 (that OMV 6 is based on) goes EOL in July, so I'd expect OMV 7 sooner rather than later.
i know omv isnt an os lmao, i meant i didnt flash the preconfigured installer thingy os from the omv site. i just flashed debian lite, set some stuff up and then installed omv with the script. also, are there any paticular reasons omv6 wont work on debian 12?