These:
https://mategear.com/products/sexy-mens-swimwear-mini-tights-ryu-sook-iv-x-tra-low-flat-front?variant=41805170049107
look ideal to wear with a jockstrap, for example:
https://www.jockstrapcentral.com/productdisplay.php?product=17301
Ergo wear has good sports thongs in my opinion:
https://www.deadgoodundies.com/ergowear-max-mesh-thong
Gregg Homme also has sports thongs but I never tried them:
https://www.deadgoodundies.com/gregg-homme-room-max-air-thong
Maybe this one?:
https://www.misterb.com/en/mister-b-leather-thong-b2cen-200700
All the stuff I bought from MrB was very good but I never bought clothing from them.