Some very old remotes used what effectively amounted to high frequency tuning forks. Example: https://www.theverge.com/23810061/zenith-space-command-remot...

No, not all were IR.

But all of them made by "LG" and featuring a single-chip design are either IR or RF.

Those will still have a ceramic resonator in them, as they’re cheaper than a quartz crystal. Hard to imagine them being audible, but not impossible.