You certainly can run text editors on Apple Watch.
For example: https://apps.apple.com/us/app/tot-mini/id1644609331
Whether it's a good idea to use a tiny watch screen as your text editor, on the other hand...
For example: https://apps.apple.com/us/app/tot-mini/id1644609331
Whether it's a good idea to use a tiny watch screen as your text editor, on the other hand...
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.