Include Rogue Stormtroopers
The collapse of the empire began after the Emperor was killed and the second Death Star was destroyed at the end of Return of the Jedi. Despite this, the empire didn’t simply just disappear, as at the time, there would have been thousands of other units of infantry spread out across the galaxy.
As previously stated, not too much is known in the new canon about what happened between Return of the Jedi and The Force Awakens, but we know that over that time period that the New Republic was established and the First Order was created from the remnants of the Empire.
Between those two movies, there was definitely a lot of disorder in the galaxy, and it’s possible that in the final days of the empire, maybe a few groups of Stormtroopers abandoned their posts and went into business for themselves in the outer rim.
Like the Jedi, Stormtroopers are synonymous with Star Wars and definitely should be included, but if this show is to take place away from the mainstream themes of the republic versus the empire, this could be a creative way of doing it.
This rogue Stormtroopers could be occupying a planet in the outer rim, but doing it on their own accord and not on order from the empire. Like they are traditionally portrayed, they would be oppressive and unwanted by the planet’s inhabitants, but make them a little rougher than we’ve seen.
Have them going around collecting taxes from the inhabitants for “protection”, quartering people’s home and show that the people are afraid for their lives. Make it feel kind of like and old school western, where the outlaws are taking over a town and the hero has to go and drive them out.
With that said, the protagonist doesn’t necessarily even need to directly engage with these rogue Stormtroopers. They could act as a driving force leading to him going on a journey off-planet, or they could have collected something of value of him which he now needs to steal back.
If a violent conflict with them were to arise however, it could be an amazing action sequence for a guy dressed up in Mandalorian armor to take out an entire group of Stormtroopers as a lone gunman, and an old school standoff is something that we have yet to see in a Star Wars film or show.
Either way, if you ask me, Stormtroopers are a MUST for the show.