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A developer by the name of obrien654j has shown off a Sega CD FPGA core running on the Analogue Pocket.
In the video, which was posted on Reddit, the developer notes that "the core has good audio timing," but they are "still working through some boot reliability issues, and FMVs stutter here and there."
Nonetheless, it would seem the developer is pretty confident they can nail all of this down, as the release is teased to be "soon".
Released on December 12th 1991 in Japan, the Mega / Sega CD is a bolt-on upgrade to the Genesis / Mega Drive which delivers games on compact discs. This allowed developers to fit in more data, as well as animated cutscenes and CD-quality audio. The Sega CD also boosted the power of the base system via its faster CPU and a custom graphics chip.
However, with around 2.24 million units sold worldwide, the Sega CD wasn't the commercial success Sega hoped for. It would be discontinued in 1996.
A Sega CD core already exists for the MiSTer FPGA, but it was long assumed that it wouldn't be possible to get it running on the Analogue Pocket. As we've seen so many times in the world of FPGA development, the impossible has a habit of becoming possible when talented developers are involved.
Thanks to MegaZXRetro for the heads up!