While currently Total War Saga: TROY is exclusive to the Epic Games Store, it appears Feral Interactive are still planning to bring official Linux support with a port onto Steam in 2021.
A Linux port was planned, and was actually confirmed when the game was originally announced back in early 2019. It later went exclusive to the Epic Games Store, which of course messed things up for Linux because Epic Games still won't support Linux with their store. Still, it will release on Steam in 2021, because that's when the exclusive period will be over.
What caught our eye was that Feral Interactive ported it to macOS and put that live on the Epic Games Store, and when this happened any mention of a Linux version was removed from Feral's famous upcoming port radar and this caused concern with readers emailing in about it - thinking it was cancelled for Linux.
Thankfully, that seems to not be the case. We emailed Feral Interactive who confirmed today that was a "technical glitch" and the Linux version of Total War Saga: TROY now appears again on their upcoming port radar list.
Feral mentioned they will make an announcement as soon as they have news on the game for Linux, which is the expected response, as of course they can't give out any more details until Creative Assembly / SEGA themselves do about the Steam release date.
You can wishlist / follow Total War Saga: TROY on Steam.