That could not be more true.
Canonical (at the time they still backed the project) would have liked us to think about Ubuntu Touch and the Ubuntu distribution for PCs as two flavours of the same OS -- as in iOS vs. MacOS. Many users unaware of technical details may believe that to this date.
The truth is, for all but a few exotic devices (like the PinePhone), Ubuntu Touch does not even use an Ubuntu Linux kernel! It bundles a minimal version of the device-vendor supplied Android system, including its kernel and driver blobs. It then uses compatibility layers (libhybris) to interface