I think there is a lot of usability work still to be done. You can only sign in to your instance with your credentials, not at any other. Other instances should preferably give you a button to view the post you're currently looking at in your own instance. So click the button, type in the address of your instance, and it redirects you to your own instance with the post you were viewing already open. Right now you have to copy the address of the post you were viewing and paste it into your own instances search field, or get to the post in some other way on your own instance.
This is particularly problematic when a post links to another post using a full URL to the post. If you click that, you get moved to the original instance that this post is on, which may not be the instance you yourself are on.
This sounds more confusing than I believe it is. If you have an account on beehaw.org, you can only interact with other posts if you're currently viewing that post on beehaw.org. If you're not on beehaw.org, you have to find the post you want to interact with on beehaw.org first before you can interact with it.
I'm trying to come up with an analogy. Like... uh...
Imagine you're borrowing a book from a library. This library also has the possibility of borrowing books from other libraries if they don't have it. But once you've borrowed it, you can't just go back to any library and hand in the book there. You have to hand it in to the library you yourself have borrowed it from, which can then send it back to the library they borrowed it from. You always have to go through your own local library because the other libraries might not know who you are.
Maybe that's stretching it a bit. I'm definitely all ears for better analogies.