This is an FOSS project, not a commercial one. Adding RIL support is not
a priority right now. Not to mention, with many different modem vendors
and chipsets, it would be near impossible to create an universal driver.
The only RIL driver that was ever written for Android x86 was that for
Huawei modems, but it was removed due to lack of developers willing to
maintain it.
Also, why are you still using those USB sticks when mobile WiFi routers
are available ?