BPS Space channel on YouTube made a collaboration with Mark Rober on a self landing rocket with a small engine, and all the experts they contacted would just stop responding the moment they asked something about the final phase of the flight. They later learnt that export controls bans those individuals from even discussing such topics with them.
Smart bombs just need to get to the target coordinates. A reusable rocket needs to get there with zero velocity, while pointed straight up, with minimal pitch/yaw/roll.
Pretty much all of the barge landing failures shown in "How Not to land an Orbital Rocket Booster" would have been accurate enough to put a warhead on target.