Is the DJI Matrice 5T's RC Plus 3 Enterprise controller compatible with other DJI drones?

No. The DJI RC Plus 3 Enterprise, which comes with the DJI Matrice 5T, is not compatible with the Matrice 4 Series, Matrice 4D Series, Mavic 3 Enterprise Series, Matrice 3D Series or Matrice 350 RTK.

The Matrice 5T does not support Dual Operator Mode (two remote controllers controlling one aircraft).