I'm not sure about this product.
Are you asking for the exact firmware that shipped with your watch when new?
Here is a link to example sketches at the LilyGO repository:
https://github.com/Xinyuan-LilyGO/TTGO_TWatch_Library/tree/master/examples
To be sure, you may raise and "Issue" on this site, which may take a long time.
I have found that a nice inquiry at their office address works:
sales@lilygo.cc
Also LilyGO suggest this GitHub repository:
https://github.com/sharandac/My-TTGO-Watch
Hope this helps!
-Terry
A