Ty so much for elaborating on this, @AlexD10S 
Just if you haven’t checked out the Build > Tools > Open-Source Stack page in the Polkadot Wiki yet (Open Source Stack · Polkadot Wiki). There you’ll also find a bunch of stuff (e.g. related to ink! & Frontend which I’ve just PR’ed/updated a couple of weeks ago myself).
Regarding the ink!athon Boilerplate & the useInkathon library we’re really getting more and more traction here esp. because of the recent Encode Hackathon. We also just opened a new Community-led ink! Developer Group on Telegram. 
One important caveat here when referring back to my initial post: Substrate Frontend ≠ Substrate Frontend. Even though most of it is based on polkadot.js/* packages (unfortunately), it’s still totally different to interact e.g. with pallet-based stuff or with smart contracts. So just as a heads up, when collecting resources it’s important to highlight these differences esp. for newbies.
Example: For anyone building/starting with ink! I wouldn’t at all recommend the generic Frontend Example you linked above (contract-integration missing; lots of unecessary stuff). But instead our Full-Stack ink! DApp Boilerplate (probably biased here 
) or maybe the useink examples.
All the best! And happy to collaborate in any of such efforts. 