If so please tell me the status of the development of the device so that we can share notes on how to get it fully running.
For your convenience: https://wiki.postmarketos.org/wiki/Google_Pixel_3a_XL_(google-bonito)
Looks like there are no standard images available, so you’ll have to follow the standard pmbootstrap installation guide (https://wiki.postmarketos.org/wiki/Installation/Using_pmbootstrap). Can’t say how well the device is supported, either it’s not very well supported or the wiki page never got updated.
You should look at the wiki page for the Pixel 3a, it is the same as the Pixel 3a, just different screen size and battery capacity.
It is extremely well supported. The only thing that might be annoying is that the microphone does not yet work, but a kernel dev apparently already has the patch and just needs to push it to git.
Even eSIM works.