I successfully installed postmarketOS onto my Pinephone Pro yesterday. I can confirm accounts that the device is wicked fast compared to the Pinephone, and the software is surprisingly mature for how new the device is.
I'm posting a boot log here as well, obtained over the serial connection in case folks are curious. I see a few odd things (kernel offset it wrong, several files report invalid ELF headers), but hey, it works. In this particular log I think the battery died after the login prompt came up, as the system locked up after, but I confirmed with a successful boot that the log doesn't differ, so it should give you a good idea of what's going on.