gh-159003: Document Flet in macOS, iOS, and Android guides (#159042)

Adds Flet to the list of GUI options for macOS, iOS and Android.

Author: FeodorFitsner

Doc/using/android.rst

@@ -33,6 +33,7 @@ much easier experience:
 * `Briefcase <https://briefcase.beeware.org>`__, from the BeeWare project
 * `Buildozer <https://buildozer.readthedocs.io>`__, from the Kivy project
 * `Chaquopy <https://chaquo.com/chaquopy>`__
+* `Flet <https://flet.dev/>`__
 * `pyqtdeploy <https://www.riverbankcomputing.com/static/Docs/pyqtdeploy/>`__
 * `Termux <https://termux.dev/en/>`__
 

Doc/using/ios.rst

@@ -25,8 +25,9 @@ your Python code is then packaged as a standalone bundle that can be
 distributed via the iOS App Store.
 
 If you're looking to experiment for the first time with writing an iOS app in
-Python, projects such as `BeeWare <https://beeware.org>`__ and `Kivy
-<https://kivy.org>`__ will provide a much more approachable user experience.
+Python, projects such as `BeeWare <https://beeware.org>`__, `Kivy
+<https://kivy.org>`__, and `Flet <https://flet.dev/>`__ will provide a much more
+approachable user experience.
 These projects manage the complexities associated with getting an iOS project
 running, so you only need to deal with the Python code itself.
 

Doc/using/mac.rst

@@ -241,6 +241,9 @@ A number of alternative macOS GUI toolkits are available including:
 * `wxPython <https://wxpython.org>`_: A cross-platform toolkit that
   supports desktop operating systems.
 
+* `Flet <https://flet.dev/>`_: A framework for building cross-platform desktop,
+  mobile, and web applications in Python.
+
 
 Advanced topics
 ===============

Platforms/Apple/iOS/README.md

@@ -7,9 +7,8 @@ Python distribution.
 
 These instructions are only needed if you're planning to compile Python for iOS
 yourself. Most users should *not* need to do this. If you're looking to
-experiment with writing an iOS app in Python, tools such as [BeeWare's
-Briefcase](https://briefcase.readthedocs.io) and [Kivy's
-Buildozer](https://buildozer.readthedocs.io) will provide a much more
+experiment with writing an iOS app in Python, use one of the tools listed in
+[Using Python on iOS](https://docs.python.org/3/using/ios.html) for a much more
 approachable user experience.
 
 ## Compilers for building on iOS