As far as size GPD seems to get it right. There's a premium on their prices though!
https://www.youtube.com/watch?v=ewgSx-HtBHU
For the phones. I've heard good things about the Gamesir G8's. I haven't tried it myself, but I've gifted one to a friend who says he liked it.
https://www.androidcentral.com/accessories/gamesir-g8-plus-review
