If you can get away with it, you might want to use PDF instead of PNG for stuff like that. At least it will be scalable in the editor (if these are compiled though, test the results).
That aside, I’d add a little inline annotation below or beside the screenshot with some text like “Open Original”, and then throw a file system link onto it.
Yeah, and for the whole board you could export as PDF, import that into the binder, then add the .scap as a bookmark to it. The advantage there is that the text of the board will be added to the search index.
Otherwise, in almost every way, it’s more convenient to toss the .scap into the binder, or an alias to it. The result is almost the same (well, macOS 15’s Quick Look is broken but that’s not a permanent problem).
But that’s all for slightly different use cases then snippet screenshots; figured it worth mentioning despite.
I use this method I have a scapple project for my characters . I like the different way to visualize the data. The document bookmark works well. A pdf is great but a static point in time. As I write I update my scapple character profile as add medicine.