As for the show why was Kim surprised? She’s the one who wanted more scams... Didn’t the first board he saw tell him they didn’t find him sincere and in one year they would evaluate him again. Was there a loophole I missed?
Only other prequel I could see is a Gus one... as there is still very little known about his "past", a fact that they hint to constantly in the BB universe. A Jessie post-BB vehicle could be somewhat intriguing... including something where the Saul post BB scenes in Omaha lead to something else. Or, just leave it be... BB ended just fine and allows everybody to draw conclusions of what happens to Jessie for the rest of his life with his new-found freedom.