Discourse is great: Asking me to write one long post instead of many smaller ones.
I would love to! If I could include more links …
Anyway, if you look for more hands-on documentation I can recommend UK Home Office again:
Plus, the W3C WAI (Web Accessibility Initiative) curates APG (Authoring Practices Guide) in case you have to use ARIA (Accessibility Rich Interface Applications):
I think, I will leave it at this for now.
Do you have some specific topic I can help with? Perhaps create a new one and link this there so we can have some high level overview here.