In the manual it says:
"Note that Polygon 2.0 does not offer a timestretch algorithm so the samples will speed
up and slow down as they deviate from their root pitch in either direction."
If you don't have keytrack turned on then the sample stays the same pitch. If you adjust the coarse/fine tune then the sample pitch changes but the sample also plays back faster for higher pitch and slower for lower pitch - so you can't change the pitch and speed independently. Keyfollow acts the same as adjusting the pitch and plays the sample faster/slower in the same way.
So I'm pretty sure the answer to your question is no. I've played around a little by attaching an LFO to the start time and stuff but can't really get more than glitches. If you're after timestretching you need to look elsewhere.
There is no synchronise to tempo option, only retrigger and play forward/backwards. Hope that helps/answers your question.