What's your reasoning? Don't see anything that benefits either of those. Polearm proficiency might work out for monks, potentially. Hard to imagine it being particularly good though.
Gwm
Polearm mastery
Sentinel
None of those feats require polearm proficiency, and both of those classes can benefit from their proficiency bonus with polearms without polearm proficiency. Monks can use quaterstaffs, warlocks can pact boon their weapon. The only gain there is that a monk could use a polearm other other than the quaterstaff, which admitedly might be of some value, but I wouldn't get too excited about it.
As I say, could work for monks, not particularly good though. Long way from 'bis' monk, and of no value whatsoever to warlock.
