If you are looking to do this on the cheap,
The rotary hammer can be used to do some slight boring.
I found acceptable control using a bosch brand carbide masonry drill with a relatively weak 1.1 Joule impact force M12 Fuel can do some surface removal, but in the material of the brittle brick, the hole is kind of nasty, its not nice like drilling out a buncha holes in metal to ease grinding.
The bigger ones that run on 18V batteries are like 5 J, while the top of the line dewalt construction ones are about 14 joules, and a serious jackhammer begins at like 25J
I also found some diamond hole saws that can possibly be used to assist this, but they are EXPENSIVE, I don't want to wear them down. I was not particularly impressed with the life span of these from youtube videos, I don't remember what I bought em for. You can do the metal working technique here,which is to drill a bunch of holes on the profile of the curve using this thing.. i Just wonder when tis gonna wear out.. and then you have the interior left, so you need to beat that out.
I really wonder if you can get similar performance from some kind of home made concoction. That video makes me think not so easily. I am not impressed with the stuff people make on forums etc.
I would like to coat the interior walls with this stuff after to make it even more robust
https://www.amazon.com/ITC-100HT-Ceramic-Reflection-Refractory-Protection/dp/B01LWI8V0G