My AidPods Pro became unusable after ~2 years. NC had some overcorrection issue I guess, created this loud crackling sound when it tried to cancel out a noise.
Rob Walling is solid and has a great reputation among SaaS founders, particularly those who choose to self-fund their companies rather than go the VC route.
He's been running a great event for bootstrapped founders called MicroConf. It's legit.
If you look at the endorsements for the book (Peldi, Derek Sivers, Patrick Campbell, Courtland Allen...) you'll see that they're as real as it gets.
Jason Cohen wrote the foreword for the book. (He founded WPEngine, one of the largest Wordpress hosting companies, with more than 1,000 employees, and before that SmartBear which got acquired for around $2 billion.)
If you're curious, you can also check out Startups For The Rest of Us, where he's been releasing new episodes for more than 10 years. I think that's one of the best ways to get a feel for whether he's someone you'd want to learn from.