Natig45, you have pinpointed the tricky part — it is hard to find places that feel genuinely relevant without every contribution turning into a pitch.
A useful way to think about it is to put relevance and audience fit first, before the link itself: would the people reading that page plausibly be your actual customers or readers, and would they trust that page? A link from a page like that beats dozens of unrelated ones, and that is also why more links are not automatically more valuable. A few relevant, editorial links will outperform a mass of low-quality ones, while irrelevant links can look spammy.
Then flip the order around: contribute something useful first — a clear answer, a short guide, useful data, or a tool that fills a gap — rather than asking for the link. When the value comes first, any mention follows naturally, it does not feel promotional, and an editor is much more likely to keep it.
The same test helps with directories. Only consider ones that are genuinely relevant, human-reviewed, and somewhere a real customer would actually look. If you would not point a customer to it, it is probably not worth chasing for a link.