Looks like I finally got an answer to my question from June 2022 (https://merveilles.town/@mikael/108401281619205878!. Yes, there is a way to have an actually useful Atom/RSS output of your Mastodon feed: https://granary.io

Not sure if you can filter out boosts. There's an "activity id" field. I'm not sure what it does.

I’m so happy to be able to “mark as read”! 🥳