I get this link from Steam's homepage right now: https://store.steampowered.com/category/visual_novel?snr=1_4_lunarsale__genresquarevisualnovel
For example, "Nekopara" is among the featured titles.
Your wishful thinking is very unconvincing.
The image on Steam's homepage that leads to that page doesn't look like porn at all.
The point here is plausible deniability, and its counterpart of assuming good faith. With that in mind, look again at the Steam's visual novels page, assume someone doesn't know the contents of the games, and see which ones look dodgy. If Nekopara looks like porn to you then you're using knowledge about the series, because the title cards of those games look like kids' cartoons.
I'd say War And Roses looks questionable, Some Some Convenience Store looks dodgy yet tasteful, and I'd almost posted this message before the images at the top scrolled round to Tricolor Lovestory. Based on that, I could easily believe that someone working for a publisher could check what's on Steam and see nothing dodgy.
The Demon Lord's link on GOG's homepage is also quite tame, but remember the images that GOG used for the Venus Bloods.
DD & Ji Ji: octalot:
No offense but no one force you to install an adult patch to enjoy a visual novel .
Does that have any connection at all to what you're replying to?
Does GOG even have something in place to prevent the porn games from being seen by minors? I know on Steam you specifically have to go into settings and enable adult games to see them.