Did you consider the approach of scanning through the readme and looking for urls to known donation sites? Maybe this could be done separately to add to the list?
Yes, but fetching full npm package metadata (which includes the readme) for 100s of packages was really slow. I'll see if there's some other approach (perhaps getting the readmes from GitHub, or perhaps pre-processing all package readmes) that might work.
Sure, that would work. Then we'd be getting the readme version for the latest version, ignoring updates to the readme that have been made since the last publish. Will consider that approach.