This seems cool but maybe not for a production setting requiring concurrency? I just signed up on PAYG which offers 3 concurrent sprites. I only see an option to upgrade to 10 concurrent sprites.

Without getting into Kurt's galaxy-brained take on the declining importance of "production" in a post-AI world, I'd say: yeah, run prod apps on Fly Machines, for more predictable performance, scaling, and pricing. Do exploratory computing --- "figuring out what you'd run on a Fly Machine" --- in Sprites.