Can frida be used in python to wait for Android app spawn ?

[a2t2]

In frida-trace there is a -W option that can be used to await spawn, i.e. one can specify API filter with -j flag for a Android APK and use -W to have frida wait for the app to be started.

In python, I see the following APIs:

frida-python/frida/core.py

Line 821 in ebd797e

class Device:

1. device.spawn(package name) and device.resume(pid) --> spawn process to attachable state, resume process from attachable state
2. device.attach(pid) --> attach to a process to give session

frida-python/frida/core.py

Line 571 in ebd797e

class Session:

1. session.create_script() --> create a new script

So based on the above, it appears the app has to be started before JS scripts can be added to monitor APIs.

My questions are as follows:

1. How is attachable state defined ? Does it mean process has started executing ?
2. Is there a way in python to match behavior of the -W flag, i.e. mention which scripts need to be loaded before app process is started, and then start the app process ?
3. Does spawn / resume by default starts the main activity of the specified app ?