The closest to that that I’ve made is in my FE8 Free For All hack, in the Arena mode Link to the post for more information and video . The other modes in FE8FFA do have a lot of AI vs AI still, but there’s also player units. In most of my other hacks that you can see in my profile here I also have NPCs in every map, so you might be interested even if it’s not exactly what you asked.
I’ve also made patches for FEBuilder that let you change whether the player or AI control each of the factions, which you could use to make blue units controlled by the AI.