The Ruby implementation (Asciidoctor) is a separate implementation by a different team. I recommend to use it together with Antora (Asciidoc's answer to Sphinx).
Sure, that seemed likely. The python repo seems pretty unambiguously deprecated, however.
Except that the version most distributions that are ridding themselves of python2 are using is a new python3 ported version. As far as I know the maintainer of that repository isn't touching it anymore, which is why it isn't linked. https://asciidoc3.org/