Sorry. Webapps not alive. I let that account fizzle and stopped paying.
If you plan to make a webapp, I would use css to edit the design screen size. Then you can work in an environment that is the right dimensions. Alternatively, I still feel bubble is superior for webapps if that is your primary target.
Still though, if you plan on only having a PWA intended for mobile phones, thunkable would be the route I’d take. If you want a webapp that also has desktop features but has a companion PWA , use bubble.