Specifically in electronics there are actually milspec versions of some microchips, different from the consumer grade ones (they have a wider range of operating temperatures plus I also believe higher resistence to electromagnetic radiation and mechanical vibration, similar to microchips “for automobile use”), but I suspect that when it comes to actual consumer electronics devices the words “military grade” are not a protected tag (as in, electronic devices said to be “military grade” are not forced by regulation to have certain characteristics) so those words are generally marketing bullshit.
It depends, sometimes milspec is very demanding. For example, crayons need to be non-toxic even if you eat the entire box.
Specifically in electronics there are actually milspec versions of some microchips, different from the consumer grade ones (they have a wider range of operating temperatures plus I also believe higher resistence to electromagnetic radiation and mechanical vibration, similar to microchips “for automobile use”), but I suspect that when it comes to actual consumer electronics devices the words “military grade” are not a protected tag (as in, electronic devices said to be “military grade” are not forced by regulation to have certain characteristics) so those words are generally marketing bullshit.