Yes you can. PostmarketOS supports a ton of devices but they all have their caveats. wiki.postmarketos.org/…/Google_Pixel_3_(google-bl…

There can be some caveats however. On the 3a XL you can act as an AP for WiFi but it didn’t work as a client. I believe the Pixel 3 has issues with USB OTG so once setup everything would likely have to be configured over WiFi.