ProductHunt? Probably also outdated, though in large part because of how cliquey the site is and how hard it is to get your work on the front page.
Not sure about Indiehackers, since I've not really used it.
Wouldn't say X is where everyone is going though. It's kinda been overrun with bots and spam right now, and a lot of people are trying to jump ship to the likes of Mastodon/Threads/BlueSky/etc. But at the same time, those alternatives are also too small to be really that credible for marketing on as well.
So uh good luck.
At an early stage, experimenting is important.
Other channels work well, too, such as Reddit, Youtube, blogs, etc.