Is it possible (e.g. when developing) to send a pwa to the phone someway e..g. via usb cable without the network and serving it in https?
The use case is development, when maybe a wifi network is not available or unpractical to set up.
If your APP is fully PWA compliant, the app added to home will be an installed APK, which you can extract using file explorer(I used ES File explorer) and put it in other devices using USB connection and adb install myapp.apk for installation.
After you load the apk, it would anyways make calls to your web-server which I'm not sure how it make sense to achieve without network connection though. I couldn't think of any reason to develop a mobile application as PWA without network. You can even have a pass though internet(sharing your desktops internet via USB) by connecting via USB if wifi is not available. But developing PWA with absolute no network mode is not practical.
Update: While you can generate the APK and side load it via USB in the above mentioned way, transferring the cached assets(HTML/CSS/JS/images) might be tricky. You may have to wrap your app as a plain cordova application or Ionic kind of PWA app which uses Cordova to wrap and build with your assets. This way, your APK will be having everything it needs to run for calculator kind of use case.