Encryption extension on RCS is a non-standard addon to RCS which is not part of the standard. RCS on Android in general is also run through google servers and Jibe, and isn’t exactly an open standard to begin with.
Apple isn’t preventing cross platform encryption at all, every popular messenger (even Signal) is available in the App Store.
Even the Index, Valve’s own headset has had broken functionality for years with no fixes in sight. Valve refuses to fix big stuff like the cameras, base stations not turning on, or even automatic audio switching.
Not to mention steamvr reprojection is completely broken.