I learned a few hours ago, for unrelated reasons, that there is at least one which does. GL.iNet ship routers running their in-house build of OpenWRT:

https://www.gl-inet.com/support/firmware-versions/

https://github.com/gl-inet/openwrt

And it's straightforward to install stock OpenWRT using OpenWRT's sysupgrade method:

https://openwrt.org/toh/gl.inet/gl-mt6000#installation