In my mind G-Shock is a brand of watch and there are many different ones.

So the statement “Casio releases a G-Shock watch with fitness features” makes sense. “Casio adds fitness features to G-Shock digital watch” also makes sense. The “original” is a bit confusing to me. And judging by the comments here others, too.

I get why it’s in the headline. This fitness watch is sort of styled like the very first (= “original”, though given the plethora of G-Shock watches and their enormous diversity that seems like a weird way of framing it) G-Shock watch from 1983.

Maybe “Casio releases 40th anniversary G-Shock watch with fitness features”.

The difference is between "Company releases new product in current line with X feature" and "Company releases software update that provides X feature to current products in the field". "Company updates product line with X feature" is ambiguous between the two.

No, but there's a difference between selling a convertible Corvette alongside the hardtop and discontinuing the hardtop to sell the convertible.

This headline would read "Chevrolet adds Android Auto to original Corvette."

And it would not make sense when what they mean is "new model of Corvette gets Android Auto."

The first 'vettes were all soft tops.