My TDS3054 oscilloscope, which is far from leading-edge these
days, has this among the waveform measurement functions.
But the 0.2% accuracy, I don't know. And do you know that
your PWM signal is actually 0.2% stable? Because mine are
often not, when you're talking about DC-DCs in real board
environments. Measuring to 0.1%, something that's not 1%
repeatable, is a fool's errand perhaps....
You want to capture every pulse, that's going to hurt. The
'scope can only single-sweep to some record-length and
you trade resolution for span in any instrument. Maybe you
really need edge-time capture and post processing, with a
hell of a record length (how many pulses, is "every"?) and
a timebase & trigger suited to the accuracy goal.
I think you want a lot of things vaguely, and would benefit
from thinking (or describing) more about what you're really
after and why. It's easy to want it all. Not so easy to find
and pay for.