if I wrote a thing in Go that took in MaxMind GeoIP (ASN and Country) and also a config where you could define ASNs and Countries to deny... and then managed ufw such that all IP ranges for the denied countries and ASNs were denied.

Would that be useful to people?

I'm thinking of doing it myself, at the moment I manually manage ufw rules... all I'm really doing is blocking all hosting services and some countries from accessing sites I run, because the sites are for small communities of people in very specific geographic locations, and the amount of content leeching and malicious traffic can be reduced to "is it residential / consumer internet in the specific countries... or not" and blocking hosting companies and other countries is proving to be very effective with no known false positive so far.

I'm also curious just how large a set of IP ranges ufw can scale to!