When I had a plot-twist in my home campaign where a bag of holding came to malevolent life (that's what happens when you stick chaos-infused dragonshards from the heart of the Mournland inside a magic object and leave them there for two weeks), I portrayed the interior walls as looking like the bag's normal fabric, only massively expanded, each individual thread grown to the size of a thick cable, with pulses of magic flowing along them like electrical impulses through the neurons of a brain.
You could work something like that into the landscape of Bagworld.
I do like the concept of there being connections between extradimensional spaces. It would make a good alternative to the "lost forever in the astral sea" fate of creatures or items that are in a bag when it ruptures - they could find themselves washed up in other bags elsewhere in the multiverse instead.
