See tracker.
revelation cannot use pycryptodome as a drop-in replacement due to use of deprecated randompool. Upstream has not been active for years. So that leaves a gentoo-specific patch.
Is there still a use for this package? Maybe it's time to lastrite it.
I'm still using this as a password manager so let's not treeclean it right away :-)
x11-misc/revelation-0.4.14-r2 has been added with patches to make it use pycryptodome.
maybe that revision could be stabilized finally :)