Yeah, bar-ends, twist grips and MTB levers are all easy enough in thick gloves. I've not ridden a bike with STIs in winter gloves, but I imagine they're at least as fiddly as trigger shifters. Probably something worth thinking about when specifying a winter bike.
Like I said, single speed for the ice bike. I still like to be able to use the brakes, and for me that's not a whole hand exercise. I s'pose MTB triggers are doable- thumb & side of hand. I still wouldn't be comfortable with the level of control though, I suspect.
(I'm almost as likely to allow twist grips in my fleet as The Bars That Shall Not Be Named).
Oh, I hate twist grips too. I tolerate them merely as a Reasonable Adjustment under the 2010 Equality Act, and even then only the high-end SRAM and Rohloff versions (ie. those that actually work) are considered acceptable
But they do work fine in thick gloves. Indeed, it's the absence of gloves in summer that makes them tricky.
MTB triggers take a bit of getting used to with thick gloves, but do work okay. The problem is the accelerated wear on the thumb part of the glove, due to the sliding motion over the lever.