This is the approach I took with http://github.com/protomaps/pmtiles , though it's optimized for the very specific use case of going from Z/X/Y integer coordinates to binary blobs, and takes shortcuts to accomplish that (fixed-width keys and root index page)
Funny enough I was looking into mbtiles serverless solutions before I went to bed, now I start my day browsing HN and I find this clever solution. Love HN for this type of stuff :)
