Searching for the right influencers - tips and tricks?

Hi!

This is my first post, hope it can stay.

I spent the last couple of hours trying to figure out a way to find influencers and content creators in a niche market, and I have to admit I was unsuccessful.

We have an IoT security tool (automated firmware analysis), and just by our own knowledge, we managed to find a few podcasts, youtube channels, and Twitter influencers, about 30 altogether. I reached out to them where possible, but received only one answer, so my guess is: we are too small for them. I would like to find more people.

How could I find other similar channels/creators?

I was checking influencer marketplaces, and most of them are totally B2C, maybe 1 out of 10 has Twitter as a platform included, the filters, and the categories do not work for my use case. Many of them include features I don't need, like campaign management, and they are expensive, and without a proper trial.

Any tool recommendations?
Or simply a nice process?
Or my best course of action is simply to go by keyword-based research on youtube and Twitter?

Thank you in advance!

PS. not looking for ads, we would prefer sponsored content where they explore our product. So they have to be security engineers, ethical hackers, bug bounty hunters, and such.

Cheers