Is there a Vuforia alternative that actually works on the Hololens

I have a working app that uses Vuforia markers to precisely define a coordinate system in the app. That works really well. Now we asked Vuforia what the license fee would be to use this in production and the answer was ... lets say outrageous. So I'm tasked with replacing Vuforia but should use the existing markers if possible.

I've looked at some different solutions like

https://github.com/EnoxSoftware/HoloLensWithOpenCVForUnityExample...

Is there a Vuforia alternative that actually works on the Hololens