Chlorine dioxide is not 100% effective against crypto
Comparing the efficacy of chlorine, ch...outhern Brazil.

Ozone is effective and acts 3200 times faster than Chlorine dioxide Ozone Food Sanitation

But I don't know about "portable" Ozone generators... New market for somebody?

UV is effective against crypto
Pulsed-UV light inactivation of Cryptosporidium parvum.
Inactivation credit of UV radiation for ...ater: a review.