Otherwise, you're going to do all this work, and then you're going to think of where to share it, and at that point you'll probably wish you had thought of this key step in advance.
Stuff built for "everyone" will rarely work because "everyone" is too broad an audience and too hard to reach.
Similarly, while Hacker News is a good place to post a project, it's very easy to get lost in the sea of /new and get zero attention, which could set yourself up for disappointment if that's your only distribution channel. It's better to have a smaller channel you have a higher probabilty of reaching -> think a small Discord, a small subreddit that's easy to get on the front page of, a small Facebook group, a small old-school forum. If you're part of any community on X/Mastodon that can work but I wouldn't stress about it if you're not, as there's many alternatives.
Hopefully, these are all communities that you want to be a part of and are active in. A lot of self-promotion can be forgiven in communities if you're otherwise an active member who contributes in many non-promotional ways.
The repeatability is important because that lets you iterate. Even if you front-page Hacker News, that's great, but you'll get a ton of traffic for a few hours but then you go an improve things and want another pass of attention, you can't really front-page again soon.
Of course, the most important thing is to stay motivated and keep pushing. I personally get motivated by other people caring about my project, paying for my project, etc and you sound similar based on your question, so that's why I'm giving you tips on accomplishing that. But many other people get motivated just because it's a really interesting challenge or it solves a huge problem in their life. Know thyself and what motivates you and pick a project you won't quit.
I will also note that you seem to want two contradicting things. You want to improve your Rust and you want to make money. For a given project, I'd focus on one goal or the other. And if you want to make money, frontend development is often important, HN condescending attitudes towards frontend notwithstanding. However, if your goal is just beer money just a popular repo might get that with Github sponsors.
Finally, you said you discard ideas because they're too simple. That is the most backwards logic you stated. You should be discarding ideas that are too complicated. Simple is great. Simple is the dream. Simple is unfortunately almost never easy. But one illuminating exercise is go back to popular Github repos and go to their very first commit and you'll see very often they started absurdly simple. As an example, DHH wrote the Rails frameworks in a couple weeks and a thousand lines of code and that became the dominant web framework for a decade. If your project gets popular , the complexity will inevitably arrive, there's no need to start looking for it from the start.