I got a ton of value from this book. It actually pushed me to dive deeper into profiling and eventually start building Rust perf tooling of my own https://github.com/pawurb/hotpath-rs
https://pawelurbanek.com/ it allowed me transition from full-time dev to on & off consulting and living off my side projects. I try to publish new posts at least once a month.
Friends from local IT communities that are also into "indie" stuff. But I believe it should be possible to reach out to people from online communities like indiehackers to form a group. There's also YC startup school https://www.startupschool.org/ that does matchmaking for founders.
Sorry for spamming my blog but maybe you'll find it useful. https://pawelurbanek.com/anonymous-slack-bot-income this post describes my journey to total 50k profit from my bootstrapped side-project. TLDR it took 5 years. Current MRR is at ~3k USD.
From all the "business" books I've read this one is just packed with actionable advice instead of motivational gibberrish. I've built my productivized consulting offer based on these tips, and it helped me quit full-time job over 3 years ago. So far no plans to go back.