I do like this idea of integrating SRS into doom-scrolling streams! I've wanted to prototype something similar, but built completely around your SRS cards.

For email, I think you're right it would need to be frictionless. There are some new email technologies that let you embed dynamic interactions in your email - we might play with that at some point.

So this is probably hard to do as a plugin tbh, but I'd love to explore eventually as a feature.