OpenBSD Minecraft launchers based upon minecraft-launcher-lib
You will need the py3-minecraft-launcher-lib, jdk-11 and lwjgl ports installed to be able to use these to launch Minecraft on OpenBSD. Will work on 6.9 or later except for snapshots and the upcoming 1.17 release. Snapshots now require jdk-16 which is in OpenBSD 6.9-current.
These are still pretty crude (having edit them to put in your username and password), but they work.
(Technically, you only need the lwjgl ports for 1.12.2 or earlier. Also, one only needs lwjgl3 for >= 1.13)