Awesome stuff, i have been following your posts :) you are getting strong!
I know i have mentioned this before and don´t want to be a pain in the ass so please don´t take this the wrong way :)
But.. I think you could make faster progress on the one arm stuff by altering a bit with the approach you go for. I just say so because i think the elastic bands mess with the technical part a little bit. It delays a little bit when you start really pushing the shoulder of the "resting" arm in towards the other arm and then making the exercise quite a bit more difficult. + you could be doing different pullup excersises that are fun and mixing it up always has a little different benifits.
But again, i don´t want to be a besserwisser and you are way strong, keep up the good work. Maybe just drop the elastic bands, tuck that shoulder in and you could finish that one arm pullup :)