The incest with Bernard would be the simplest to remove. By removing the option to watch incest porn altogether, we eliminate the ability to fantasize about him, and eventually kiss him. Cuts off the entire branch. Significant late-game sections of the sugar daddy route would have to get the axe, due to the whole Iris thing, as well as the corruption path with Ethan and Ash's mother.
As for the drugs, there are various mentions to coke that would have to be replaced, eliminating the potential addiction subplot entirely. It would make Eva's descent into gang-related depravity a bit harder to swallow, were she sober, but that part is just my opinion. If we are eliminating the gang plot entirely, we may as well get rid of the choice to let Eva be corrupted at all, since the only plot point beyond fucking Jack is the gang plot unless you pull her back to the light side.
Overall, these cuts seem technically doable, but very annoying, and an unnecessary shift of focus when so much work already goes into making the game what it is. The more I think about it, the more gutted a "steam-friendly" version feels, conceptually.