Prius not working. Not sure if it’s the electric motor or transmission.

There should be warning lights on your dash... Those warning lights store error codes. You can use Dr. Prius app to read those error codes if you buy one of these: Hybrid battery diagnostic and repair tool for Toyota and Lexus

 

the motors are the transmission. maybe the parking pawl failed.

 

Sounds like either the chain in the trans or the trans/engine coupler has failed.
Seen a few broken chains this site.

has the trans fluid ever been changed? You can check the chain by dumping the trans fluid into a container and see how much metal pieces are in it and on the dump bolt magnet. Won’t cost a dime.