I feel almost exactly the same as you on the subject. When I was young and starry eyed I built my own router out of a PC running openBSD, all by hand. Nice learning experience, interesting OS, but definitely not maintenance free especially around system updates as back then openBSD packages and sys upgrades required recompiling everything. Now I do the same mini-PC thing as the OP's article but I just put OpnSense on it. Agree the UI can be maddening at times but the thing is rock solid, and has very polished update and upgrade mechanisms. Built-ins/plugins are great - unbound, wireguard, openvpn suricata, backups to git etc. Also I like that it is BSD based, my network experience was learned on Cisco's and Junipers in an ISP setting and Linux networking has always driven me crazy
I've been running OpenBSD as a router for almost 20 years I think? These days, the only ongoing maintenance it requires of me is running `syspatch` and `pkg_add -u` periodically to keep things up-to-date, and then `sysupgrade` when a new release comes around. It's way more hassle-free than in the old days.