In your
other thread this week about disk encryption, you stated that full disk encryption ("FDE") was required. With a little bit of basic research I helped you to discover that both OpenBSD's softraid and FreeBSD's GELI used the same cryptographic primitives, though there are implementation differences and there are operational considerations when choosing between them.
Now, you are asking specifically about a less-than-FDE FreeBSD crytographic tool, and whether it can be deployed on OpenBSD. No, not without being ported.
Perhaps, if your needs have changed, or, you have a new use-case, you might possibly be interested in non-FDE disk encryption methods on OpenBSD? If so, you can use the same tools discussed in your other thread: the softraid CRYPTO discipline can be applied to a single filesystem, such as /home, as I mentioned to you in your other thread. In addition, I'd mentioned vnconfig/mount_vnd, which can create and mount virtual filesystems, and these can be encrypted. While this option cannot be used for FDE, it may be more flexible than softraid for your use-case. This is because the "backing storage" can be partitions as with softraid, but unlike softraid the backing storage can also be a file in a standard filesystem. While this isn't FreeBSD's PEFS implementation, it may have enough similarities that it meets your needs. If it doesn't, then perhaps FreeBSD with PEFS is a better fit solution for your new use-case.