I use this as a deep cover carry pack. It works well and hold near any sidearm I want to carry and a spare mag in the back pouch.. I also keep my phone and car keys in the front at the gym.
I suspect it could easily do 2 rifle mags in the back half and phone, pistol mag or 2 and such in the front.
I use mine primarily on a belt, so I have something at hand when in the gym doing some exercising.
I am quite pleased with it. No issues but the elastic inside the pouch parts does wear out some. I have been using it for near 3 years and it still snugs some.
Both pouches are zippered. Back pouch is front to back (R to L) opening on the zip pull and front pouch is back to front opening (L to R) in video on zipping.
There is a front slot. I do not keep anything there.
For just mags and a bit of kit the waist pouch you show would be my preference. But I do already have a single sling bag type GHB in the vehicle.
Nemo
https://www.amazon.com/Ideagle-Pistols-Concealed-Holster-Handguns/dp/B08XQ45C4L