Hello yes, that should work. I just did a test with my "old" PS4 and the "new" PS5 headset, so it works. However, when using 2 headsets, 2 players must also be logged on to the console. So not only one can play and the other only listen. The PS makes a link with the registered controller(s), i.e. player 1 and player 2.
It may be possible to register other headsets with the PS5, but I only have two...