What non free software is necessary to run this hardware? Is there an Intel ME equivalent?
Yes, all AMD chips [1] after 2013 come with an equivalent to the invasive and vulnerable Intel ME [2].
It's arguably worse, since we have some known ways to reduce the scope of the Intel ME backdoor [3].
But realistically, if you care about security and privacy, both Intel and AMD chips are unusable.
1. https://libreboot.org/faq.html#amd-platform-security-process...