What exactly is the problem?
I had no problems booting FreeBSD.
I don't think OpenBSD is any different.
OpenBSD won’t even initialize on UTM/AppleSilicon for me.
For OpenBSD, the installer works after adjusting the devices in the guest.
https://cdn.openbsd.org/pub/OpenBSD/7.3/arm64/install73.img
- UTM / Create New Virtual Machine / Virtualize / Other
- Select 'Skip ISO boot' / Continue
- Hardware / (adjust as needed) Continue
- Storage / (adjust as needed) Continue
- Shared Directory / Continue
- Select 'Open VM Settings' / Save
- Right-click on Devices/Display and select Remove
- Devices / New / Serial
- Drive / New / Import and select install73.img
- Edit the VM again and move the second VirtIO Drive to the first position by right-clicking on it and selecting 'Move Up'
If you feel inclined, hop on to the UTM Discord and the folks there (me included) should be able to help out.