For what it's worth (not much; there's no real utility value here) I just told the Tap, "simon says, Alexa, play prime music jazz", walked over to the Echo with Tap and told the Tap "repeat" and it gave the command and got the Echo playing Prime music jazz. Big deal. other than knowing that Alexa understands Alexa.
Re, the Dot in the closet: OK, keep the Dot out and next to the closet, get an appropriate mini stereo audio female to male extension cord long enuff to run under closet door, and plug that into the stereo's input. Now, your Dot is more useful and not kept in purgatory anymore. You can only hear it through the stereo, though. Maybe you have an old iPhone, etc with BT not being used for anything today other than as a paper weight. Well, use that to send commands to stereo, perhaps.