I have a Pixel 4a5G and it is still going strong with CalyxOS. In fact, they are about to release Android 15 for this device, which lost all its support from Google at 14. Using one of these open source, pro-privacy alternative OS’s is the only true way to degoogle your phone, so I would suggest buying a new or used unlocked Pixel phone. I will never go back to running on pure Google again.
It is probably because they are creating their own Linux FireTV OS, moving off Android. Amazon and Google have always been at odds. It is the reason Amazon created their crappy App Store, because Google would not allow their app in their store. I think Amazon is further distancing itself from Google.