I bought the GL-AR750S a while ago and kept it stock. It’s a customized version of OpenWrt with an “advanced mode” that lets you get into what I believe is just the regular wrt configuration portal.

I didn’t have anything that the router couldn’t do from VPN to repeating to spoofing Mac to get through cafe-style portals at hotels.

Looking at their website, it looks like their newer models still use wrt openwrt.org/toh/gl.inet/start.