I can barely make out a Hyperkin logo in the lower left of the packaging. That actually explains the "DDR" thing, believe it or not - one of Hyperkin's online storefronts is DDRgame.com.
Still doesn't answer the question of who the original manufacturer is (since Hyperkin typically rebrands stuff from Chinese OEMs), or what the interface looks like, though. My guess would be Qi Sheng Long (a.k.a. Hamy), who manufactured several of Hyperkin's clone consoles such as the Retron 3, but I'm nowhere near certain.
More findings!
Apparently there's a Coleco-branded version of this same console out there as well - see, for instance:
https://www.onlinecharm.top/rare-coleco-plug-and-play-virtual-kickboxing-p-19204.htmlFrom the screenshots, I can confirm that this is
not a variation of any of the following boxing-related plug-and-plays:
* Conny's "TV Virtual Fighter" (also distributed by SDW as "Virtual Kickboxing")
* DreamGear's "Boxing Champ" (16-bit from Macro Winners)
* Macro Winners' "TV Boxing" (8-bit, also includes VT03 Famicom ROM hacks) - also sold through Hyperkin's DDR Game brand