Twitter and Tumblr seem to be one of the main-hubs for VN news. If you could post your updates there then that could draw some attention. It will be small or barely non-existent. If another dev or dev team, with some followers, share your post then that's a different story. Then there are blogs that specialize on this type of content like VNs/romance or sci-fi. Problem is, the only Tumblr blogs I know of, who act as a content-sharer, are deep in Covid-wasteland and are barely active because of that.
Sadly I'm not part of any Sci-fi or gaming group/forum. I think you'd have much more success with getting people to try out your demo on the right discord channels. Again, I'm only part of 3 channels and one of them is from another small dev, who's parody fan game got pulled down by itch.io. ...
As for writing something else to build up some foundation, that's a good idea. Problem is: Does it even interest you? Do you even like to write high fantasy or will it snuff out any interest in continue writing?
If you want to go the last route, remember that "magitech" is a thing. It's basically your bog-standard medieval or baroque setting with magic that is more handled like technology (powering street lights, ect.). The main protagonist can be a detective, a disgruntled soldier of war or some heiress of one of the biggest "powerstone-thingy" provider, who gets involuntarily involved in all kinds of political power-struggle... for example like succession game the princes and princesses play for the throne.
Lastly maybe sleuth around other indie VN devs that have much more experience when it comes to selling and marketing games. The Lemmasoft/ren'py discord server seems to be a good start for that. They even have an introduction section to introduce your idea game: