So, main idea is to expose inventory api as part of public API and add some extras logic like ability to tweak IItemHandler extractor like here.

Main purpose of this staff is ability to simplify inventory interaction for mod makers and allow to create peripherals that will populate same inventory peripheral interface for blocks, that even don't have an correct inventory handler (like inventory manager, rs bridge, me bridge, etc) or block that require some rework to make inventory interface more clear (like storage drawer)

Another option for inventory population, instead of registration logic make interface method for peripheral to handle this logic itself

or even copy of as interface to allow peripheral casting to different objects