I used to have a pretty successful browser extension that I shut down because the site it worked on shut down.

I grew it by adding features that people would ask for on the site's forums, for example a user would say "hey can we have x feature?" and I would respond saying "great idea, I added x feature to my extension y!" This was very effective and over time others would start responding saying my extension had whatever feature they were asking, capitalizing on how relatively slow companies are to implement features.

This does rely on the extension having a site it operates on and having a forum for users though. If I were to do it today I'd focus on finding places where my extension's users concentrate, Discord, a community Slack, or otherwise, and doing the same thing.

I have a similar type of product that depends on a third party and I use LLMs to automate most of the work. I feed it batches of Discord/Discourse messages from the third party’s community along with a prompt containing my feature set and it flags messages that might be relevant so that I can reply to them (manually, although the LLM generates some starting points based on examples replies).

The false positive rate at first was over 50% but with some prompt tweaks and back testing, it’s approaching 10-20%

Great ideas, thanks. I've had similar success searching for common problems using Google, finding the highest-positioned Reddit result, and leaving a response with a link.