I still have a few things like Authenticator rooted on my iPhone. I mostly use hardware tokens, so Authenticator is nice to have, but not critical for daily use. Signal is another one, I'm currently using the linked devices, but I don't have a "new root" yet.

I believe there are some Google Authenticator apps for KaiOS, just not in the main app store, and I've not gone through the process of working out sideloading yet.