Well, not only are shotguns low pressure, but the powders used in them are very fast, in fact, fast for PISTOL powders. In my experience, a muzzle brake works best in guns that shoot slow burn rate powders. More gas escapes up the brake making for the reverse thrust.
Yeah, I've never worried about pursuing a brake or porting on a shotgun. The very BEST thing, in my experience, to reduced "perceived" recoil or felt recoil is a good fitting gun. Gas guns help a lot, bleed off the gas not too far up the barrel to work the action. That reduces recoil more'n any muzzle brake. You can add weight, but depending on what you're doing with the gun, that could be a bad thing. Weight is great on a 10 gauge goose gun... 20 gauge quail gun not so much.
To me, I worry more about fit than anything else. If it fits, I can handle the hottest 12 gauge loads just fine. Again, depends on what you're doing with the gun. I have shot up 5 boxes on an extended dove opening day weekend. That's a lot of rounds in a short period of time. But, hey, women shoot light O/Us on skeet. Don't get more intense than skeet shooting for rounds fired. If the gun fits, girls can handle it, so why would a grown up man complain?
Most of those dedicated women clays shooters can out shoot most of us men, too. So, really, I don't see a problem here with shotgun recoil.
Maybe I'll change my tune with a little more age and a few more creaky joints, though. I don't intend to quit hunting no matter what.