The term for pockets you add to an existing garment is ‘afterthought.’ I am inserting afterthought pockets into this jacket. This can be done to just about any garment, but sometimes it’s very complex. An afterthought pocket inserted into a knitted sweater is a major undertaking — you can google for YouTube videos showing you how.
But adding an afterthought patch pocket onto a cloth jacket is easy. The trick with this particular project is that the pockets will be on the inside front of the jacket, not visible from the outside. This will allow the pocket to cover the back side of the studwork, and also to hold my cell phone and keys. This is where a pocket will go:

And this is the actual pocket:

There’s a little finessing going on here. I want both ‘right’ sides of the fabric to be facing outwards. What you see here is what you’ll see if I hold my jacket open. Also, I want to sew both the inner and outer pieces of the pocket together, so that the actual weight-bearing seam, that will keep my cell phone from falling to the floor, is a strong machine-sewn seam and not my less-than-perfect hand sewing. And to do this I need to set up my faithful Bernina sewing machine.
Why, you may ask, am I hand sewing these patches on? Well, we come right back to those decorative studs. The sewing machine will choke, going over those. By hand sewing I can dodge neatly past them.
Which shows you that the stud decoration is also an afterthought. If they were planned, original to the garment, the ones on the edges and collar would be inserted before seaming. They’d be more secure that way, the issue of scratchiness would be evaded, and they wouldn’t lie so close to the seams. Look closely at the photo of the jacket front. Some of those studs are actually on the seams. Someone upscaled this garment once already!