It's like buses. You wait ages for a good Pinterest client for Windows 10 and then two come along at once. We had Piny UWP and now here's PinStar UWP, both polished in their different ways, but neither have a conventional UI so I suggest you try both and see which you prefer. PinStar UWP seems the less fully featured, more of a browser than a client, but it's still worth looking at.

There's no real Store description, so we'll get into screenshots:

It's an unusual UI but then Pinterest is an unusual service, so... swiping, long pressing and double-tapping, this isn't a UWP app as you've come to expect it! (right) here browsing pins from people we follow...

The top nav menu can be shrunk if needed, essentially acting as tabs for three different application modes...

Searching for a pin clue and then browsing matched pins/items...

You can grab PinStar UWP in the Store here. It's currently free, but will go up to a dollar in due course. Comments welcome, I'm not sure what to make of it, but then I don't use Pinterest for real (I'm logged in here as my wife!)