So I guess that one of the benefits of releasing AVNs on Steam is how well they can sell. I think there was even one that end up selling half a million copies on Steam, crazy stuff. Meanwhile Doujins and all of that other stuff, JP VNs don't really sell all that well. Which I believe is part of the reason for why they were also expensive in Japan in the first place (similar to anime physical sales) they don't sell that well and they have to charge a lot to those few that do buy it. But that has since changed and there was even a period of time when some were worried about price, especially because of digital. Since they could now sell the games digitally they could lower the price, but if they lowered the price that could affect how much money they would make since not that many people buy those types of games. But now that they are able to sell overseas (even though they have to censor the game) they are making more money than before.
So I played a AVN, there was no voice acting in the game. No voice acting is not that unusual (by the way I am curious about licensed music though since there are some games that do feature it) any way so season 1 of this game did not have voice acting but for some reasons season 2 does have voice acting, I'm not sure if they have gone back and added voice acting for season 1 as well since then. But I'm guessing that these types of games are making a pretty penny, not only from their initial Patreon days to them releasing on Steam about 2-3 years later.
It's a lucrative business. As of now the two most lucrative times of games that can sell pretty well on Steam with a small budget, are horror games and Adult games. Make a good Adult Horror game and then just watch the money roll in.
That is my current arm chair analysis of the game market on Steam.