I think you should install the operating system again, with the Ut installer you can do it.
download the installer to your computer, install it .
Save all the data you have on the phone before installation,
Nexus 5 is now on Ubuntu 16.04 (2020-W17)
Nexus 7 is on OTA-11
Hopefully it will work on the UBports Pinephone 🙂