OpenBSD just released a portable version of their privsep rpki-client(8)* this week!
rpki-client 6.6p1 was released Apr 13, 2020: https://www.rpki-client.org/txt/rpki-client-6.6p1.txt
* https://man.openbsd.org/rpki-client
Looks like there may be problems with the mirror sites, a generated tarball is on the official portable github, but it may be worth waiting for an official announcement as github can re-roll these (it's not an uploaded release asset): https://github.com/rpki-client/rpki-client-portable/releases