I struggle with finding rap rock and rap metal like seriously, it's impossible because all algorithms will end up suggesting either normal rap or directly metal and rock 💔

Nope. For metal the suggestions are like you said. Either generic or limited. I usually just look up "more bands like x" and use the results. Usually a mix of last.fm + reddit + other sites. Another thing I'd do is use rateyourmusic and browse by genre. For Symphonic metal, for example. Sometimes there's genre specific sites. Like the progarchives where I go as well from time to time. Oh, many subreddits also have discord servers so maybe look into that as well.