About rotation rate (= speed):
as always, integrating the rotation speed over time, you'll get the angle - nothing new to me actually. It's always done that way, even for the LEGO 1D gyros.
(edit: I see that you edited your post meanwhile)
So if roll and pitch can be calculated out of those gyro values and calculated gyro angles, it should be able to that also for yaw, as already stated.
And you are always confusing (relative) yaw with (absolute) compass heading, although I never asked for absolute compass headings!
As stated and shown, even simple LEGO 1D gyros can retrieve those relative yaw angles!
But @jremington, with confidence: I asked who actually knows such libs, and not who has no idea about it.
So @all:
which libs do that yaw+pitch+roll calculations actually well, according to experience, possibly without using the interrupt pin?