If there are fears and doubts, perhaps it would be safest to just assume the transport is clear text in risk ranking and adapt other counter-measures to fill perceived gaps.

For really sensitive flows, perhaps dark fiber + non standard ciphers + encrypting the payload with application layer encryption using non standard or custom ciphers. I mean, why not, if it's your own B2B flows. Take an existing cipher / protocol and make a few subtle changes. It's just math.

For end-user encryption, that would take some more thought and would probably get into layers of turtles.