Where do you find this mysterious product “niche”?

Since my last side-project failed I was looking where to apply my technical skills: maybe to create some business, to have fun implementing something useful, to have purposeful side project. Everywhere you look for "ideas" you'd find a common thread of advice: find a B2B niche with some unresolved (or poorely solved) problems aimed at medium/small business, where customers would want to pay for that problem solution, and try to offer something there (cheaper/better). Do an MVP, iterate on an early feedback, pivot if needed, GOTO 10.

The problem #1 is: where the heck do you find these niches? Let's assume you're a highly skilled and motivated engineer working a typical job in a big corporation. You have absolutely no contact with thousands of small businesses with all their problems: you have no idea what kinds of inefficiencies small legal firms have (that have optimization potential), you have no idea what professional landlords expect from their CRMs, you have no idea what small scale-metalworking shops have for problems. What are possible solutions to this? Networking events (hard in COVID times), endless HN browsing, endless scrolling through openstartup or indiehackers?

The problem #2 is: even if you'd find some interesting and seemingly successful niche product, you go to the landing page and are welcomed with some abstact marketing bullshit bingo about "enchancing productivity", "no coding required", "track your goals", "manage contacts" and you're like: "wtf, people are willing to pay for this?" You think: "all of this can be solved with a bunch of properly designed excelsheets and some python glue, why is there a fancy webapp for that?" How you get rid of this mindset and adopt a more business-oriented thinking?

I would be very grateful for any sorts of insights: interesting idea sites to browse, good books to read, etc.