It is possible to define your GUI as a web page (no internet required) if you are good at HTML + CSS.
For component extensions, use this search
https://community.appinventor.mit.edu/search?q=components%20%23extensions
This looks good:
It is possible to define your GUI as a web page (no internet required) if you are good at HTML + CSS.
For component extensions, use this search
https://community.appinventor.mit.edu/search?q=components%20%23extensions
This looks good: