Thank you for sharing the write up!

Not an OpenBSD expert by any means, but two small pieces of minor feedback as everything else you wrote mirrors my own setup and experience. Firstly, unless you are really strapped for space on say a 90s machine, it is generally recommended to install all the file sets as there can be interactions with ports even if one does not expect it (say ffmpeg needing X11 libraries). The general OpenBSD mindset is after all "Use the defaults" and the default is to install all the file sets. Secondly, the OpenBSD Handbook has a bit of a mixed reputation in the community from what I can tell. Unlike the FreeBSD Handbook, it is not an official document and I tend to rely on man pages, openbsd.org, misc@, and a few blogs I consider to be trustworthy instead.

As a final note, glad to see you have IPv6 up and running. I really should get around to it now that dhcp6leased has been in base for more than two releases.