Here are some screenshots in PCE resolution and palette with on-screen colors reduced well below what would be required for the background tiles-
Even an average Turbo/PCE developer should be able to pull off this level of graphics quality. Without theorizing how the players could be cobbled together with various sized sprites, if Bonk III can toss around a couple giant Bonks this size-
...along with enemies, power ups, etc... then (proportionately) arcade sized players should also be no sweat. Even if the developer was so lazy that they left the bgs totally flat and pushed the life bars and timer either to the top of the screen or striped them SFIICE-style.
I had a stock TG16 in mind, as in America atleast, addons sell pretty poorly historically [segacd/32x etc].
Historically, the TG-16 in general sold poorly and the CD-ROM wasn't an add-on for the TurboDuo. Worldwide, CDs were the more successful/popular format for the Turbo/PCE, so there's no reason that MKII shouldn't have been done on CD. In which case the music would be arcade-superior and the sampled sfx would be about as good as the SNES version, but with higher quantity.
Its hard to see how a decent MKII port on Turbo/PCE
couldn't have been the best at the time.