Despite the “tang/clevis” system being too clever by half (and even more complex), it is essentially very similar. Mandos, though, is much simpler; you can actually understand it, since it uses standard components and protocols like DNS-SD¹, OpenPGP and TLS. (Mandos is documented in man pages, in contrast to page you linked, which is both huge, and – for me at least – keeps reloading itself and replacing the entire page with a 500 server error.)
Mandos is also for Debian (and all Debian-based systems), and not Red Hat (although there is nothing preventing a port, since Mandos now also supports initramfs images created by Dracut).
Finally, Mandos was initially created in in 2007, many years before tang/clevis, and literally by a person in a dorm room, not by whatever academics/scientists who seem to have dreamed up the cryptography/protocol tangle that is tang/clevis. Mandos has changed some since then, from initially using broadcast UDP and X.509 certificates, to using DNS-SD and raw public keys², but has otherwise remained very similar to its initial design.