I recently picked up a KRAKATOA Pinatubo thong (just to check them out and they are very comfortable with a larger pouch and nice support but not a ‘bulge’ thong like Cocksox, McKillop, and others. They have a traditional thong back, fully open sides, awesome modal material that is super soft, no gaps on the pouch, just a great fit. They are also available in masculine colors and do not have any oversized branding on the waistband. Definitely something I feel comfortable wearing to the gym.
They also have the Haleakala thong with what they call the ‘stratopouch’ which is even larger. I just ordered one of these and can’t wait to feel the difference, if any, in the pouch.
One last comment, their sizing is true based on my experience as I bought a small which is a 31-33” waist.