In previous years I've found new stuff using Pandora Radio, Youtube Music, and occasionally just by browsing music communities. Reddit's listentothis sub used to be really good for finding relatively unknown bands a number of years ago.

Pandora Radio advertises that instead of doing a basic genre or artist comparison, each track they have is manually analyzed for specific aspects of the track like "call and response", "wall of sound", "excessive vamping", so it makes connections crossing genre lines.