Given the origins of the LEB, it seems like it would be a good choice to be paired with the NA28 as a diglot. I realize there would be some challenges in bringing it to market and that strictly speaking the LEB does not always follow the NA28, but I am just floating the idea. Although I strongly prefer to have the NA28 and its apparatus, as a backup suggestion perhaps Faithlife could print their own diglot using the LEB and the SBL Greek New Testament?
