But I will also say that I suspect your strategy is possibly a little naive. I hope it's as easy as you've laid out, and I'm envious of the viral aspects of your proposed product. However, I suspect the "top of funnel" portion (hypothesis 1) won't be enough to drive your "land and expand" portion (hypothesis 2). At least in my own experience currently trying to build a B2B SaaS tool [0], it's an absolute grind. And while some of these communities you're mentioning will engage, it's hard to convert that to people entering your funnel in a reliable fashion. You've got to combine it with 19 others things like content marketing, speaking at events, etc.
That being said, we're not engaging in as transparent way as you are so YMMV. I wish you the best of luck!
0: https://kitemaker.co - a crazy fast issue tracker that connects all of your other tools (GitHub, Figma, Slack, Discord) better than anything else out there