dirt/gravel roads in Virginia

You want to check the Import wiki pages.

Hi, I live in Virginia, United States and do a lot of gravel bike riding. OSM is extremely inaccurate in identifying which roads are paved and which are not.

I think it's fair to say that, in the rural US, OSM simply doesn't know whether roads are paved or unpaved. Some apps/sites which use OSM data may misleadingly assume that roads are paved unless stated otherwise, but (due to the provenance of the original data) that's not a safe assumption in the rural US. I run cycle.travel which deliberately takes a very conservative view of what's paved and what isn't - because the information simply isn't there most of the time.

Fortunately, the VA dept of transportation has a map & database of unpaved roads. If there's a way for somebody to quickly ingest that data and update OSM accordingly

It's hard. It's not impossible but writing automatic conflation code (i.e. take the VA data, find the matching records in the OSM map database) is really tricky. You can probably get a best-guess estimate in many cases, but going from there to something that doesn't stomp over previous mappers' hard work is a challenge.

As @SK53 says a MapRoulette challenge might help, or alternatively someone could take the VA data and make a background map from it which is easy for mappers to use as a reference. (I did that with the US Forest Service map data, for example.)

I looked for a licence for this data, but could not find one on the VDOT site. It appears under the rubric of "Open Data", but without a proper licence it is just not clear whether the data is compatible with the ODbL licence used by OSM. A starting point might be to contact VDOT and clarify the licence situation.

There are around 6000 entries in the data, and no doubt some have already been correctly mapped on OSM. If the data is usable it might be better to use it to drive something like a MapRoulette challenge rather than trying an awkward job of conflating it with existing data (which may be unreconstructed 2008 TIGER data).