fate of emperor varis at the end

[Nalien]

A single soldiers that would be invincible in combat is worth more than 100 conscripts.

Echo =/= invincible, and as far as anyone knew, that's all Project Resonant did, give people an artificial Echo. The whole point of the Project was to create Echo soldiers to fight Primals without fear of Tempering, not to make invincible soldiers, or to pursue immortality. It was solely about reducing casualty numbers versus Primals. When making a single Resonant has a higher body count than just throwing bodies at a Primal though, why bother? It was a failed project, one entirely unexpected and unknown result in Zenos immortality doesn't change that.

On top of that, they have cloning technology.

Cloning technology that is seemingly imperfect at the moment. The clones have no soul or artificial soul, they're just husks. Given the Echo is very much soul based, one imagines their current clones would be completely useless for Project Resonant. You cannot imbue a clones soul with the Echo if that clone has no soul. Remains to see whether the Empires cloning project progresses beyond its current point at all.

This would absolutely be technology worth looking into. The project was bigger than one man, word would have gotten out.

This is going to be the last time I bother repeating myself with this because this is getting absurd; Nobody knows Project Resonant made Zenos immortal... Christ, it was even a surprise to Zenos in the cutscene we first got a hint that he survived... How can word possibly get out when nobody had any idea what even happened? It's a recent development, long after the entire project was completely shut down by the Eorzean Alliance. On the Garlean side at least, there is nobody left to piece together Zenos' immortality with Project Resonant, and thus continue the research... Nobody on the Garlean side even thought Zenos was dead since Elidibus took to puppeting him immediately...

Could word get out now? Sure, though I don't think anyone who now knows would be incline to spread that information. Varis is probably dead. Gaius probably doesn't want to help effectively make more Ascians. Estinien will tell the Scions, we'll have Lyse and Cid speed up investigating the remains of Project Resonant, but we sure as hell wont be reviving the damn thing, we'll just want to understand the science behind it so we can formulate a means to actually kill Zenos this time. Could word still get out via a spy or something similar? Perhaps, but again, for the purpose of this topic that is completely irrelevant... Unless the spy has access to Exarch level time travel, I don't see how such information about Project Resonant now coming to light can be used to help Varis survive... There is just no way that, in the seconds between learning that Zenos is still alive, and being cut down by Zenos, Varis managed to continue research into the Resonant, iron out the ridiculously high casualty rate, and do it to himself to become immortal to survive...