How about just prompt the user, and then let them set the default right there by checking "use this location in the future (can be changed by going to preferences > screen recording > screenshots and selecting a new default location)".
I could probably write this is a day, and I haven't used spring since college.
I believe any good thing you can say about crypto will eventually be coopted and controlled by capital.
The same is true for all "disruptive" technology unless it's built specifically to be hostile to monied interests, like the fediverse - and even then, you have to continue defending it against incursions.
Silence of the Lambs, Anthony Hopkins.