> Is this opensource My first gen is open source https://github.com/Amber-Williams/language-flashcard-app-gpt... if you'd like to repurpose it

This one has a fair amount of security and wrappers around the latest update I plan to repurpose for profit so unfortunately this project is not. Though I'm happy to share how its built if you have questions.

> compatible with existing anki decks?

No its not currently. How would you like it to work with Anki?