I've had some success using the Kindle app highlight feature - highlighting key points as I go along, and then later reviewing just my highlights (which can also be exported). You can add notes to the highlights too.
Where did you hear that?
Edit: Looks like your link to the sibling comment is for extracting annotations from pdf. Are most of the books you're reading on remarkable in pdf format instead of epub?
This way I can go through my annotations sequentially, save highlights / their main ideas, and reformulate my notes into plaintext a bit more clearly.