Two that worked better than posting:
Meetup talks. Small audiences but the post-talk conversations are where the first users come from. A single talk does not much but giving 5 talks in the same scene is a network. You don't need a big stage, local user groups are enough.
Niche with a search-volume problem but only 1-2 existing solutions. You stop competing for attention and start getting found. Harder to pick than it sounds, most "niches" are either dead or already crowded, but when it works you skip the audience-building step entirely.