If you buy a power supply you start with two things: One, it meets the recommendation of the manufacturer in wattage, ie "450W" or whatever they recommend for that card. Next, make sure it has the necessary pci-ex 6 or 8 pin connector required by the card you choose(if it needs one). Even if you buy a 500W PSU for a card that only needs 400W it still won't work if that PSU doesn't have the right connector.
For PUBG you'll want an Nvidia card, since that game runs better on Nvidia cards right now. At 1080p a GTX 1060 would be a good choice. You can run the game on less than that, but then you'll need to compromise on framerate and/or settings.