That looks like it lets you manipulate some kind of notes object. I wouldn't really call that a text editor.
I don't think there's an app that lets you just edit arbitrary files which can be read by other apps or transferred to/from the watch with something like ssh, just these weird canned things that depend on network services run by Apple and/or the particular developer.
I don't think there's an app that lets you just edit arbitrary files which can be read by other apps or transferred to/from the watch with something like ssh, just these weird canned things that depend on network services run by Apple and/or the particular developer.