Valkyrie Drive is out on Steam. You get a slight discount if you own Senran Kagura Shinovi Versus, IIRC.
The port is awesome- gotta be the best one yet from Marvelous. Here's footage of it playing in 4K resolution at a solid 60 FPS.
Obligatory
Tried installing it on my GPD WIN and it even scales down really, really well- I can run it at a resolution slightly lower than the Vita's 960x544 res and get a rock-solid 30 FPS on low settings, and that's with v-sync enabled. It plays much better than the the Vita version for the smooth framerate alone.