It may have changed in the last year or two but last I knew third party camera apps can only access the primary camera lens which has severely limited their potential since phones began adding additional cameras. Moment(the company that makes mobile phone lenses and gear) has a really solid app but they quit developing their Android version because manufacturers wouldn't allow them access to the other lenses on the phone and it crippled the experience compared to iOS.
Personally this is one of the reasons I won't touch a Pixel phone. Google may arguably have the best computational photography(better than Samsung, debatable against Apple) but simply picking up a camera and shooting in auto allowing it to decide the frame rate and exposure severely limits the capabilities of the camera. The average person taking photos of their family or posting snapshots to social media don't understand this, but a photographer who understands the exposure triangle certainly does.
If you want something that will do a good job in most situations when you just pull it out of your pocket and shoot a Pixel is a solid choice, if you want to decide how your images turn out it's a horrible choice.