This project shows the bind off with the nubbin in the 3rd photo down.
Elastic bind off (RS) K1, [ k1, insert LH needle through both sts on RH needle, k2togtabl, rep from to marked st,
This is a knit together through the back loop. Insert the LH needle into the two sts on the RH needle with the LH needle to the front, k2tog tbl.
At the marked stitch: knit this st (do not remove marker),
bind off 1 st by k2tog tbl,
place rem st back onto LH needle,
cable cast on 1 st, bind off 1 st by k2tog tbl (these 2sts are the one replaced onto the LH needle and the cable cast on stitch),
insert RH needle into the center of marked st and pull up a loop (this isn’t so easy to do but it’s possible. A crochet hook might help.),
bind off 1 st by k2tog tbl (these 2sts are the stitch remaining on the RH needle and the loop pulled up from the center of the marked stitch]
Then continue with the k2tog tbl until the next marked stitch.