Can we also pull magazines from our backpacks and equip them to the suit item ports instead of reloading my currently held weapon, so that I can stock up my suit item ports?

In the current situation, no. The repooling process will reload your weapon. However, to quickly stock up your suit item ports, you can just open up the loot UI, and then with a single mouse click you can move your backpack mags to your suit. Very easy. It's going to take a second. So it can be done easily, but not automatically.