I was helped by @marCi002 answer, but it became much more straightforward now I think this should be more than a comment :

1. Edit your ##YOUR_REPOSITIORY##\.dart_tool\chrome-device\Default\Preferences file. (It should exist, if it does not exist yet, try to run the target using Chrome at least once)

2. Change the value of the key you want (currentDockState to undocked for me)

3. Enjoy on the next launch of Chrome through Android Studio

From my understanding, this ##YOUR_REPOSITIORY##\.dart_tool\chrome-device\Default is the template that is used each time you launch a debug session from Android Studio. So it's a trick, but it allows you change some settings.