"military grade" isn't a protected phrase. As a consumer you might be able to sue them if the thing breaks and they can't prove that phrase meant anything? But doubtful.

Claiming to conform to a more specific product or process standard would be more specific fraud.

But in general though "military grade" is a red flag for shitty marketing.

Example: pop tarts are military grade! [1]

Though their commercial packaging is likely not.

https://www.dla.mil/Portals/104/Documents/TroopSupport/Subsi...