[OtinG]

You can pair two Echo devices which are the same model and generation. For example, you can pair two Dot 3rd generation Echos to create a stereo pair. You cannot pair unlike models though. I’ve got two Dot 3rd generation Echos paired into a stereo pair. The sound is surprisingly good for devices with a single 1.6 inch top facing speaker. I doubt even a stereo paired set of Echo Dots will sound better than the speakers on a decent TV though, unless the TV speakers are messed up or the TV is a really cheap budget one with crappy speakers. It would be better to use a set of full size Echos paired for stereo, but that would run into more money and still might not best the speakers in the TV. One advantage to using an Echo or Echo stereo paired set, or the HomePod as far as that goes, is that you would have voice control of the audio level.

It sounds like the new HomePod mini has a conical part in the bottom that projects sound all around 360°. The Echo Dots, even the new 4th generation, don't have that. So that might make a difference as well since the new Dot 4th gen has a front facing single 1.6" speaker. The HomePod mini should have better sound than the Dots.