I am aware that upvoted posts make it to https://kbin.social/fav however that just doesn’t work well as I already have 1,000+ pages in there. Moreover, that only registers upvoted posts and not comments. A workaround would be to just use boost, and only upvote when you want to “save” but that is just not conventional imho. The ability on /r to simply save a comment or a post is truly basic but effective.
EDIT: Relevant Codeberg issue
I would like this and my 2 feature requests would be:
available as ?secure?ish? RSS feed
Do not limit to 200 items like reddit. If it must be done, notify the user so they can save older content