Gotcha, we'll try to add "anal variants" of existing scenes. Not gonna promise it in the next update, but we might drop it a small patch in between two major expanshions.
Great to see you guys trying to add stuff like this. Once suggestion I have would be to maybe have a slight branching path for this, so the setup and dialogue for the scene can be specific for the anal version.
For making an anal variant, the one that comes to mind the most is probably the D.Va scene, it's also doggy which works well and the side view art wouldn't need to be changed. Maybe you could have an option where the MC knows D.Va is desperate to get back at Sombra and he uses that as leverage to do anal. Like, before the scene it could be: "I'd be willing to help you out, but ... [ANAL]" as a new option as well as one for continuing down the existing path. An [ANAL] tag could be good for people that want to stick with the vaginal scene. Also I think Sombra could have an different reaction line later for anal.
Overall though, I'd much prefer having only a few anal variant scenes with different dialogue/reactions etc. than it being an option for all scenes with only the art changed.
Also, a smaller update that could help too would be expanding the anal route for the existing Mercy one. Maybe having it be it's own additional task after the main path finishes. Like maybe a quest where she wants to/is convinced by MC to do more extreme testing.