Hi, K, maybe I can help you.... 'kay ???
the ASUS portable monitor is compatible with any Mac that has a USB 3.0 port/socket on it and uses ASUS' driver for it
If you have Catalina, then ASUS says use driver version 5.2.1
If you have Mojave, then ASUS says use driver version 5.2
If you have something older than that, say 10.13 or earlier, ASUS stays stick with 4.3
I don't own an ASUS monitor, and I don't work for them, or Apple, just a Mac user here same as you.... so if ASUS says use that
or stick with this one, why argue.
as for the USB-C VGA Multiport adapter (apple made) to connect to the USB 3.0 monitor connection, yeah, that'd work...
that adapter does have a USB-C passthrough which is nice, along with the USB 3.0 and VGA port. You might not need the VGA port, but oh well.....
if you don't care about USB-C passthrough, you can get a USB-C to USB 3 adapter for cheap ....link
https://www.amazon.ca/nonda-MI22SGRN-Smallest-Aluminum-Indicator/dp/B015Z7XE0A
from the same website, roughly, you can get a usb-C hub for a bit over half the cost of the USB-C VGA multiport adapter,
and most of 'em have at least 6-7 ports on them, maybe a few more......
something to think about anyways....
I wouldn't want to totally dissuade you from buying the Apple adapter. though
john b