Anyway, seems neat! I had some work shorts on a summer job years ago, funnily they were mostly like cargo pants, but they had an additional pocked very similar to your proposed one. It could be used for a folding meter stick (or whatever it's called in English) and that pocket alone made the shorts perfect. It allowed easy storage and access to a frequently used tool which was almost unwieldy long.
Do you plan to sell something like this online?
Even the US startups that are making clothes to customized measurements, etc, are forced to stay price-competitive by using the same overseas factories that (in addition to the specific kinds of inflexibility I bring up in the post) are often labor rights disasters, which is part of why I make my own clothes in the first place.
If I had a clear plan of attack against fast fashion, I'd probably take it, but the best I have right now is individual action.