You want to gate off the front door? If so, it looks like you'd need to hire someone for a custom job.

Instead, I'd cover the "stone" with the same stucco as the walls next to it, including the interior of the entry. No security gate.

I was thinking about doing something like this

Based on the way the walls are built, that entrance does not look like it was meant to house a gate. I would just stucco over the exposed part or add matching stone to redo your entrance. The only entrance I could easily find that was similar to yours does not have a gate. I am guessing that you could get a custom gate made, for $$$, but I personally don't think it would be worth it.

Lake Conroe Spanish · More Info

I agree it’s not what the builder intended but I’m going to frame it in and stone it, then fit a door like this in there. This house gets a huge amount of wind from this side, and it’s not really a main entrance for occupants either. This door should create a nice mud room and break the amount of dirt and debris blowing in too.