I dont really know how HTTP Requests work but wouldnt it be possible fo Jerboa to open all Links with an in app Browser and checking for a lemmy flag in this request? I imagine it can be janky if the in app browser first opens a new window and falls right back to the app but if this is possible, there would be no need to have a never complete list since everey instance will have this flag.
Sorry if i wrote nonsense, just an idea
Oh, i understood your way of doing it as a service that checks a list (remote or local) if this is an instance, where the list needs to be updated regulary, thats why i wanted a flag that tells the service "Hey, i am a Lemmy instance!" when it checks every link before opening.
But yes, your implementation would be a future proof idea that would work like a charm!