Most of this setup is portable. I've set this up in
FreeBSD, Debian/Devuan 12+ and Arch linux - most packages used are available as binaries. I've been able to build a jgmenu package in NetBSD but it does not run.
In OpenBSD, I just submitted patches to move OpenBox to python3 and update tint2 to the latest version which uses gtk+3. I think the tint2 patch was accepted but I have not seen it yet in CVS. I have corresponded with upstream for tray-app/gtk+2 whose country is at war with Russia. He's looking into updating to gtk+3.
The latest version of jgmenu has it's own menu-cache utility and is faster than the OpenBSD version that still uses the external menu-cache. Edit: jgmenu menu updated in OpenBSD.
I also submitted an update to yad which was not addressed. If you use a newer version there are some syntax changes
gtk-close -> yad-close