As silly as it sounds I don’t have an old device I can test it on. Not willing to try it on my daily driver yet.
Discussion
Don't think that's silly.
But you can try to install it on a USB stick o, external SSD laying around and just booting there to tinker on it.
Runs just fine in VirtualBox for testing purposes. Bit of a faff with screen resolutions, but all resolved via the October update note here: https://github.com/basecamp/omarchy/discussions/176
I might just do that. Thanks!