MIT is temporarily unavailable for Building apps. Service might be restored later today, tomorrow or later.
Yes you possibly can develop on Thunkable. Is it compatible? :D :D :) Not completely. If you have already an existing app on Google Play you will also have to migrate the KeyStore you used on AI. You must determine compatibility by experimenting if you can load your App Inventor 2 aia on Thunkable.
Once you make the transition to perhaps Thunkable, you might never be able to return to App Inventor. The code will probably not be compatible.
You are developing commercially. It is logical you use one of the compilers designed to be used for developing commercial App Inventor like apps: Thunkable, AppyBuilder, MakeRoid etc. or graduate to the Java based Android Studio.