Chosen Solution

My iphone XR TMobile Black was destroyed via a hammer (long story). It doesn’t even turn on even if I connect the charging cable or to my MAC. I looked inside and it the “Front Sensor and Speaker Assembly Flex Cable”, “Front Camera and Infrared Assembly” and logic board are unharmed (I am assuming from visual inspection). If I buy a donor iPhone and change the above three components will it work (theoretically)?

In theory yes, you would have all you need to get it back into shape. All you will lose will be the true tone as a replacement screen would need programming to have true tone working, but I guess one can live without that as we did before.