Here's one on the Atari 800
https://www.youtube.com/watch?v=7G5CEA_P9Hc
not denying that Dune II was the first "successful" RTS but that Atari 800 game runs in real time (it is not turn based), you select units and tell them what to do (go to X, fire at Y) etc using the joystick to move a cursor and shortcut keys to select units and groups.
One historian defines it as a game which:
> ...runs in real time, ... also one where players start with a largely blank slate, gather resources, and use them to build a variety of structures. These structures can in turn build military units who can carry out simple orders of the “attack there” or “defend this” stripe autonomously. The whole game plays on an accelerated time scale which yields bursts if not sustained plateaus of activity as frantic as any action game[1].
1: https://www.filfre.net/2018/12/controlling-the-spice-part-3-...