A full speed Sega CD support (with sound) will not be easy to achieve given the fact that picodrive's latest available sources are 1.35b without support for cue/iso/mp3.
A better way to play those game is to buy a JXD s601 or a Yinlips G16/G18 or any of those unexpensive android devices (more cpu speed, a lot more RAM).
I tend to avoid playing games with a deprecated experience (like PSX without sound on the dingoo).
Anyway, i would love to see cd support for pce since there's really great games for that device (like dracula x).
Keep up the good work !