I was looking for something like this https://www.hyperstone.com/en/USB-31-Con...-2129.html which is an integrated USB flash drive controller with some RISC core. The problem is that sourcing those in low volumes is usually pretty hard, Mouser seems to at least list them for 5-6EUR per piece, but I doubt that you can actually order only a few...
Come have a chat in the Pine IRC channel >>