If I am understanding what you are wanting...

Not too difficult to replace zipper slides, but when looking for a tutorial on doing that I found this that gets you lockable zippers even easier.

https://blog.mellylee.com/2018/08/ho...-any-backpack/

Replacing the actual slides involves removing the stops, install new slides, and install replacement stops.

If you don't want to DIY, I would assume any upholstery shop, seamstress, or tailor near you could do the work you are wanting.