If it's even slightly larger than the Vita was I'm not going to get it.
The Vita was the limit in handheld size. Didn't even get a Switch because there was no point. It was too big to be considered a handheld, the portability didn't matter, and you could play all the games on PC either through ports or emulation.
Knowing Sony, they'll attempt to do some form of streaming to it from a PS5 and then make gimped versions of PS5 games to play "on the go" instead of making dedicated games for the system.