Assuming you play with the following rules:
If you're holding a power card and you draw a card since you can't end on a power card, can you then play the power card instantly (in the same turn like rule 2) since you have 2 cards now?
According to these rules
If the player has no matches or they choose not to play any of their cards even though they might have a match, they must draw a card from the Draw pile. If that card can be played, play it. Otherwise, the game moves on to the next person in turn.
You need to play the card you just drew. So you can not use the power card.
I'll assume that the house rule posed doesn't contradict the other rules, one of which is that it is explicitly illegal to draw a card and then play a card that one could have played. Drawing a card by choice disallows one the right to play from one's hand later that turn (and if you weren't drawing by choice, you don't have that right anyway).
That said, may I propose a house rule that allows this? If you don't want players to just hoard wild cards to win, one could impose If one's final card is a wild card, they may play it, but must draw one card so that they still have one card left at the end of their turn (and as such, must declare "UNO" or be at risk of being caught)".
