Being able to mark post as read, and have them be hidden from my feed. Or hide posts I have upvoted/downvoted.

Also it would be really nice to have the ability to group communities together from my view point. So instead of a single lemmy feed with all of my subscriptions mixed together I can have multiple feeds each based on say a single topic. Say I have a group called Gaming. and in that I have !gaming@lemmy.ml and !linux_gaming@lemmy.ml !gaming@beehaw.org etc.. etc.. I think this would also help the issue with having similar communities on multiple instances. For example We have !technology@lemmy.ml !technology@beehaw.org I could subscribe to both and just use a single group to view them both. Instead of having to view one at a time.

Yeah. Joining communities from other instances is a hassle. Kinda puts me off sometimes.

Automatic discovery of communities from instances your community knows about.

I'm almost reluctant to post suggestions about what I'd like to see on Lemmy/kbin. It feels kind of entitled, you know? It's early days and there are obviously lots more important things to get stable and established first. Not to mention the devs are doing this for free and about to come under a lot of pressure. As a dev myself, used to listening to users making subjective demands about the "right" direction to take an app, I fully sympathise :)

That said, my offerings for the suggestion pile would be:

1. Discoverability - finding and joining communities isn't intuitive at the moment. This seems to be a fediverse problem rather than a lemmy/kbin problem, as Mastodon has similar issues. It should be as simple as "search for a topic, hit subscribe". Instead it involves copy pasting cryptic strings of text, editing them sometimes, then searching, and a bit of hoping. I think this will be the number one issue that impacts adoption.

2. UX - more one for lemmy than kbin, but there are improvements that could be made to the UI to improve user experience. A general tidy up to improve visuals (things like alignment of community names without icons, for example), ordering of lists of communities, external links opening in the same tab (appreciate some prefer this, but it tends to lose your place in a feed).For kbin, easy access to your list of subscriptions would be great.

Honestly, most of the UX stuff is low priority compared to getting the apps stable and coping with scale. I hope they figure out those wider challenges though, because there's definitely a lot of promise here.

Fix the deletion of comments so that the content is removed rather than just flagged as deleted.

A small quality of life thing, but some way to mark notifications as ‘read’ automatically, either when i click through to view it in the thread or when i vote on it. Maybe I’ve missed a setting somewhere, but when someone replies and I go to read/interact, the notification number stays there until I manually go and click ‘read’

I'd love to see a poll option :)

By far my biggest thing is RES style keyboard shortcuts

The second for me is going to have to be automatic instance redirection

I feel like the request in the OP can be fixed by some kind of community digest that gets shared as instances federate with each other, and then on a recurring basis afterwards.

Basically Lemmy needs support for this: https://git.asonix.dog/asonix/relay to do what you want.