As it turns out, without the hardware-observe connection, devices plugged in before the snap is started don’t work (see the above thread for more information).
This auto-connection was already granted to Firefox, where it solves the same issue.
+1 from me too - this has been a long-standing bug in both Brave and Chromium (cc @nteodosio - you should also add this plug from chromium and request auto-connect too by the sounds of things)