Install Debian fasttrack-archive-keyring / enable Debian fasttrack repository by default?

[grass]

They have an onion.
http://5phjdr2nmprmhdhw4fdqfxvpvt363jyoeppewju2oqllec7ymnolieyd.onion/
not listed on https://onion.debian.org/ but https://fasttrack.debian.net redirects me to the onion.