I didn't found solution for this, so maybe it's time to request this :)
How about create bigger page, than actually size of display and let user to scroll it, like on smartphones. Drag background to scroll.
the Nextion product-line is designed as HMI device. A screen-scrolling is neither doable with its limited ressources nor would it make a real sense within a feasible and good HMI design ...
How about cropping just page and -top -left (minus) positions to hide elements (or fragments) from page.
For this, there is a vis command that will hide and show elements as desire.
There is ZERO "Virtual Pages" or partial "Virtual Pages" to work with.
If it doesn't fit in the pixels of the display - then it doesn't exist.
This is the reason why there is no scrolling.
If the display has 480x320 pixels, that is the total canvas to work within.