Take a look at Musicroamer
you type in a favorite artist and it uses the spotify recommendation stuff to find similar artists
if you find one that sounds nice then you can then create a branch of artist that are similar to them
(probably a horrible explanation, just mess about with it for a minute and you'll get an idea how it works)
I've personally used it to find quite a few new favorites since ditching Spotify in favor of a self hosted Navidrome server
as for FLAC downloads check out Qobuz, which has unlimited DL plans
alternatively if you would rather sail the seas, search up Firehawk52 for a guide