I've decided that this will not be part of the initial launch of the BfA Overhaul. This is going to be an extremely sizeable module and I need to do a lot of research to figure out how best to build this and also learn the relevant Blizzard API's.

However this is not completely off the cards and I will be eventually working on this it just simply won't be in the next public release.

Blooblahguy has an excellent example of a lightweight method for making a one bag frame with bdBags http://www.wowinterface.com/downloads/info21055-bBag.html

I've had a ganders at the code for pretty much every bag addon I could find including bdBag. Was an interesting prod around but the dependency on bdCore meant I didn't dig far as I can't be bothered juggling between the two attempting to piece together another developers code.

I'm definitely going to be revisiting this however in the mean time I've found Baud Bag to fit both the functionality and style requirements I had in mind so have just been using that. Some niggles with it that I'd still want to change so this is far from off the cards.

The older versions before the rebrand didn't have the bdcore dependency, however the code does error for the keyring if I remember right.
I used to package a modified version of the code in BobUI I don't remember what all I fixed though.