Previous generation of vex “393” motors used a well known servo control method, so it was almost trivial to use them with third party controllers (like Arduino or NodeMCU).
However, V5 uses a propitiatory control protocol over RS-485 link, which I never seen openly published.
If you have to use V5 motors and sensors you may consider having your third party controller talk to V5 brain which, in turn, will control V5 motors and read sensors.
Otherwise, there are plenty of mature open source sensors and motor controllers that will work with STM32 out of the box.