I think the price discrepancy between PLYCF and NWWV is due to the following reasons 1) The trades and volume don't show up till the end of the day so no flippers want to touch it. 2) There is some uncertainty over whether shares bought after the 17th of July will still get the 1:1 NWWV shares. If the 17th was the last day to buy PLYCF to get NWWV then the price decrease since then is understandable.
Supposedly, once the merger happens and we get our NWWV shares, PLYCF will file for bankruptcy and be auctioned off as a shell. So NWWV is the price to watch for now.