https://21lessons.com/  by  nostr:npub1dergggklka99wwrs92yz8wdjs952h2ux2ha2ed598ngwu9w7a6fsh9xzpc   / I recommend buying the print edition on Amazon to support our fellow #nostrich

https://learnmeabitcoin.com/ / someone just posted this as a good resource, looks to be comprehensive as well