Yeah, I've gotta agree w/Clint (draft edit: and others) on this one. Atari was already going under when the CD came out. It also added nothing other than the ability to read off CD-ROM instead of cart. No extra processor, no extra RAM. Even the first CD-ROM add-on (PC-E/TG-16) had cards that added RAM to the system. The Sega CD added another 68k processor and additional RAM. The Jag CD? Nothing. OK, redbook audio. Even the pack-in games were pretty sad offerings. The Nintendo 64 had a measly 2 launch titles in the US, but one of them was a Mario game and people knew they could trust Nintendo to deliver the goods. Who was trusting Atari to release great titles for a CD add-on for a doomed console?
I think fighting games probably would've been the best use for the format, loading the new background and character sprites between rounds. The Jag could pull off beautiful 2D games, so fighters of the day (within limitations, obviously) would've made a lot of sense. But none of that matters as the Jag itself was a failure.
I see little to no market for the JagDuo Mini, outside the more hardcore gamers most people either don't know about or have long forgotten the Jaguar. While I could assemble a list of cart based games that'd still be popular today with casual gamers, I can't think of an original CD release that anyone would care to play in 2019 or later. The main accessory I'd hope they'd include would be a diode to prevent reverse polarity from blowing up the system.