Saw that you own. I’m not an handyperson and have never done this but could you rent one and drill holes in the mortar, then tap in those little plastic plugs as anchors for screws?

I’ve seen that done for attaching house numbers to brickwork but the mortar was my own idea.

Mortar may be softer to drill into and easier to repair on mistakes or removal than the brick (someone else pipe up if this is a bad idea)