Yeah, I'm definitely inclined to say that any and all KotOR material that is brought into canon is Filoni's doing, at least up to this point where there has not yet been a "canon" narrative actually set in that era.
Moraband (a canon take on KotOR's Korriban) and Darth Bane in
The Clone Wars:
To that, I will add that I absolutely adore the Darth Bane design in TCW, with his mask that is obviously intended to be evocative of Vader's own helmet, albeit with a much more ancient styling.
Then there's Malachor in
Rebels:
And
Rebels offers the potential implication that the crossguard lightsabers date back to that era, given that Ezra finds this among the wreckage of an ancient Jedi vs Sith battle that happened on the planet:
There's the Krayt Dragon pearl in
The Mandalorian:
And all of the talk in
The Mandalorian about the ancient battles between Mandalorians and Jedi "Sorcerers" in ages past, which is even visually represented in murals on Mandalore in
The Clone Wars:
And while not from the KotOR games, the Darksaber is an invention of George Lucas' for
The Clone Wars that spans all three series and can be traced back to Tarre Vizsla, the first Mandalorian Jedi, which is would make it a relic of the Old Republic era:
