Make the FO a small warlord faction or make them a faction trying to topple the Fel Empire after the Imperial-Sith war. Kylo Ren has to go, Rey needs to be nerfed, Snoke is a waste of space.
Knights of Ren vs Imperial Knights could be good. With jedi as 3rd faction, only serving the force.

I’d also like to add that Imperial Knights and Cade Skywalker were better representations of moral ambiguity/ gray jedi in Star Wars than Luke Skywalker rejecting the jedi order which doesn’t fit his character.