Not sure if you have seen my post on here about my smoker.
I have not got any questions about it but plenty of views.
There are several ways you can attach your frame to your brick depending on your design and the tools you have to work with.
Here is what I did for mine.
Three of these corrugated masonry ties were welded on each side at the correct brick coursing and mortar placed on the bottom and top of them as the brick was laid up.
If you do not have a welding machine you could drill a hole thru your angle and bolt the ties to it.
Another way you could attach it would be to use bolts.
This was a carriage bolt I had laying around. You could drill a hole as large as the square portion on the bolt head at your mortar joint location. Pack mortar around the threads. Use a nut on the inside of the angle at the bolt head or not. Your choice.
Your mortar joints should be around + or - 3/8" thick. I would think a bolt around that size would work. Put a nut on the end of the bolt so it does not pull out. Opposite end of the head.
Once your mortar cures it is not going anywhere without force.
My doors are 1/4" steel so they will last awhile.
There are a bunch of ways you can build your smoker. It depends on how long you want it to last, your skills, tools and the most important. Budget.