Using a GL-MT300N-V2 for a mesh network

I was curious if the GL-MT300N-V2 ( router can be used to setup a batman-adv mesh network ( I understand the device only has a 2.4 GHz radio which will limit speeds. The router is 16/128 and has the MTK7628NN chipset. What I cannot piece together is if the router runs openwrt out of the box or a custom version of openwrt. Can the router run a mesh network with batman-adv? I am willing to install stock openwrt if need be.

If you want to try out mesh, you can try, that is a customization over openwrt that builds meshes automatically... so you can try it out.
As your model is not included in the standard builds, you will have to build it yourself, but it is pretty straightforward!

Yes it can. I have good experience with 802.11s/batman-adv with openwrt.