nostr:npub1rvwnhzkvllph6ulm93fg9wvs4agaqwgagpkyl27q6m5wlp6g9gqqvcxgew the Megadrive should work with SCART (if my memory of it is correct) so the OSSC or GBS will handle that just fine.

Dragon32 is composite - which won't work on those.

Personally, I'd avoid upscaling etc. Let your HDTV process the plain signal. All the post-processing stuff seems to add noise in my experience.