The #RaspberryPi hurdle that #OpenBSD fell at was its installer.
Despite it presenting two different partition table editors, I couldn't persuade it to just simply use the already existing single UFS volume that was already there. It just does not seem to cater for the idea that one might want to install to the same removable DASD that one is using, with boot, system, and swap as already defined. It either led me down a path where it zapped the existing partition table, and all of the install files, or demanded that there be another solid-state medium to install to.
Which is sad, because a Pi with just a TF card and a single purpose is still a significant use case.
Whereas in NetBSD's sysinst, choosing to install to the same system is the first option on its third menu, after picking the installer language and choosing to install.
This is a 2 horse race being comfortably won by #NetBSD, currently. I've not tried #FreeBSD yet.