I think it would be cool. Also after seeing many of Ben's portable conversions of many platforms, and of course the TurboExpress/PC Engine GT were the first handheld consoles to play TurboGrafx-16/PC Engine HuCards....
I am curious how a TurboDuo conversion to portable would be.
The only problem with using a TurboDuo for the conversion, is that it is very rare and be a shame to dismantle(I never should of sold mine in hindsight).
Maybe a just a standard PC Engine, with CD-ROM2 and system 3.0 card or Arcade card shall do. Sorry the SuperGrafx is too rare too and a shame to dismantle as well.
However, there is other ways to accomplish what you are looking for, and that would be using a Raspberry Pi and emulator for example.
My apologies for the late response, I just joined this site.