Bright sun is always a problem with LCDs, I'd add it often is with EVFs too. I will say the GR III has a pretty bright LCD when it's cranked up to the +2 setting, which I can set via the quick functions on the toggle. Combined with the highlight-weighted metering and blinkies, I can get enough to go on from the screen even in the brightest sunlight. But yeah, an optical VF with information displayed in it is the best tool for bright sunlight. Even though I'd say I take more photos in lower or more interesting light than full overhead sunlight, as I don't typically like how digital looks during the brightest conditions. But for EDC, an OVF as comprehensive as the X100's would be sweet.
I would say the GR is the only camera I WOULD classify as pant pocketable.