I wonder how high I can push the polling rate on Quest 2 for the controllers.

I know OpenXR runtime can handle at least 240 Hz (this is what CloudXR library polls at, asynchronously, to lower remote controller latency).

The big pain point for using Touch Pro controllers on any PC VR headset, is the need to manually recalibrate each session, dependency on OVR API, running two compositors at the same time on your PC. Ugh

Aruco Markers should solve the alignment problem. Plenty of projects use it:

Isn't aruco tracking imprecise for gaming? Maybe, I guess it depends on the framerate, sensor fusion with IMEs...

With Touch Pro controllers, you don't need aruco for that, just during setup / initialization to auto-calibrate and align the tracking spaces from Quest 2 to X HMD.

One interesting thing I noticed with Monado's Android OpenXR runtime, is that it's shipped as an APK itself, meaning, I guess it runs as either a service or just a DLL or something, not sure. Then your OpenXR app links to it or calls it.