A beta is currently available on SideQuest: https://sidequestvr.com/#/app/339
The PC version of boxmania.club has some limitations but it is playable and good for testing created content: [link]
(Control: the hit boxes are mapped to 1-8 number keys. Can also use QWERHJKL)
A theme customisation template: [link]
all customisations go into /boxmaniaResources folder, check it out, tinker!