100% agree. Did the same back in early OAuth2 days, before main platforms got libraries and support (we were transitioning from OpenId 2.0, not yet OIDC ). OAuth2 spec is surprisingly straightforward and readable, couplet with basic understanding of ABNF that is used in all RFCs - it was a joy to read and implement. And this understanding also stuck with me for many years and helped massively in my career :).