The last time I replaced a unit was in 2012, but I think what you would be looking for is a head unit that accepts camera input , a wiring harness for the head unit to the car's wiring, a reverse camera adapter if the car doesn't use the standard yellow RCA-esque connector (apparently toyota uses several different connectors), and a interface adapter if you want to retain the use of the steering wheel controls which in total would probably be <$500 depending on parts. I remember Crutchfield's "will it fit" tools and advisors being pretty helpful.

Looking around a bit, apparently there's also a neat though slightly more expensive product called the datalink maestro rr or rr2 that does the camera and head unit interfacing part while retaining additional features.

https://youtu.be/AkWzSXFJYTo

Toyota themselves have started offering upgrades of older models to support CarPlay or Android Auto. Costs about $200.