Just check instances to see if they have donations.
Another thing that would help is if there was a way to link to a post/comment that wasn't an https URL. E.g., you can link to a community like ! community@instance and when anybody clicks it, they'll go to their instance's view of the community, but when you link a post it's like https://instance/post/whatever so it navigates you away from your home instance. This is just in relation to the "seeing dead links" aspect. Because even when an instance goes offline, other instances will still have copies of the posts from it.
