Ok they are sweat proof insofar as sweat does not damage them or leak through them. But the droplet beading technology that they were advertised with a few years ago didn’t work for small droplets and also did not work well for big ones after some time, and the claim was withdrawn IIRC.
I do wear a cap or suchlike to stop some sweat but when working hard the sweat often wins.
The Halo sweat bands have a rubber strip that stops sweat running directly down your forehead. It’s not perfect, the band itself will eventually become saturated, but it’s better than a cap or Buff. And when sweat does build up you can feel it beforehand and wipe it away before it drips onto your glasses.