W-8BEN is the easy part. After that it seems to depend a lot on country: some people register as self-employed, some invoice, some just declare it as other income. Not looking for official advice, just what's worked for people. Mention your country so it's useful to others.

Platform marketing pages all say "up to" something, which doesn't tell anyone much. If you're comfortable, drop field, platform, rate and rough region. Once there's enough I'll make an anonymous table and pin it.