At last, at least one meaning behind the mysterious [P] is revealed.
It took a while to understand the reason behind the painting of Thor in Q's drop #290. Thor is the ancient story of Jesus the Messiah, pre-told. This is all about the return of the Christ (aka Thor, aka Jesus).
Now examine the ancient name for Thor as it's written in Old Norse thusly: Þórr. Or in runes, as in this related pic.
The significance of the [P] becomes obvious.
Yes, frens. Q is the word of God. We're in the final countdown, and the best is yet to come. Q really did save the best for last. Because He is coming.