It’s the voice line that makes it seem that way to me, more so than the “I made Snoke” line. I would agree with your impression just based off that, but the fact he says he was every voice in his head, including Snoke, makes me thing that Snoke was only a vessel that Palpatine spoke through.

But I guess that is what bugs me about the movie/novelization. It doesn’t really make anything clear. Palpatine made Snoke, but was he his puppet or his servant? Did Snoke know he was serving Palpatine? Was Palpatine a corpse or a clone? Did Palpatine FUCK, or was his son a test tube baby? It feels afraid to give a concise answer, so it leaves everything ambiguous.

I guess that is why I like the idea of Palpatine clones in the vats instead of Snoke, because it gives you a visual answer as to how he is back. Not just a Dominic spitballing ideas to the audience. I guess I like that in the same way I like Snoke being trained by Palpatine. It lets Snoke keep his agency, but still makes him a pawn of Palpatine. So, you could make that voice line just be, “[Palpatine voice] I have been every voice [Vader voice] inside your head.”

You could leave it as-is, too. But like I said, Snoke being his own character with his own goals makes Kylo killing him in TLJ more satisfying, IMO. It doesn’t have to be that way though of course.