At $21 it sounds like an absolute bargain. If they were available locally for that price then I'd definitely pick one up, even though I think most Atari 2600 games have aged horribly.
I haven't seen one in the flesh, but from the reviews, they appear to be using the same front end and (probably) the same hardware as the 2018 edition of the Sega Genesis Flashback. If that's the case, then you've got nothing to worry about. I recently bought a 2018 Sega Genesis Flashback and it's a very solid system.
I think it might actually be time to re-evaluate Atgames. The company itself is shady as hell, but most of their recent products have been pretty decent, once you factor in the price. Fortunately, they've moved away from using crappy proprietaty hardware and software. Their newer systems are mostly based around tried and tested open-source emulators running on Linux. So there's very little they can screw up. Even their new front end is pretty decent, if a little bland.