Indie hackers is definitely great for this kind of content. I'd also recommend "Startups for the rest of us" [1], "The art of product" [2], Patrick Mckenzies blog [3] and Stripe Atlas guides [4]. The first three resources all pretty much describe how to bootstrap SaaS-companies, while the Atlas guides are more general guides for businesses. Finally there's an excellent episode on Reid Hoffman's podcast "Master's of Scale" interviewing the founder of Mailchimp [5].
The Mom Test (Book) is a way to verify the thing you're building people will actually want. Providing market-fit can be hard.
Startup School by YC is another good resource to keep you accountable and make progress with your ideas.