It would be possible to connect both the PIMORONI HyperPixel 4.0 touchscreen:
and a standard 7 "raspberry touchscreen:
to a Raspberry 3B+ ?
Connecting them won’t be an issue, getting them both working at once “might” be though. I frequent the Pi Foundation forum and can tell you multi display support is in Buster. And that one of those screens can be the Pi Foundation touch screen. I’m not sure how it works when one is connected via the GPIO though. You should likely also ask this question on the Pi Foundation forum. I have Pi Foundation touch screen, I don’t own a Hyperpixel though. Plus I have yet to try dual displays. I’ve been meaning to try it out but can’t find my round 2it. ;)