I assume that about 20% to 50% of the home routers, Access points and Wifi mesh devices sold world wide are based on OpenWrt. Often some old versions of OpenWrt with many vendor modifications, the UI is always custom.

I know that the main vendor SDKs from Qualcomm, Mediatek, and Maxlinear are based on OpenWrt. I think only Broadcom uses an own Linux distribution which is not based on OpenWrt in their main SDK. Linux has a market share of about 99% in this market, I haven't seen VxWorks in any recent home router or access point.