It is possible to install both Home Assistant and openmediavault on the same Raspberry at the same time ? if so how? who can help me
Not sure how a RPi will cope with both but I run both on an HP T630 thin client
There is even a proxmox openmediavault installer script on @tteck’s page linked in that thread.
I already have Home assistant working on raspy, do I have to reset everything?
If you want to do proxmox, then yes.
However a backup, then reinstall via proxmox and restore your backup should work.