I've read from a blog that exporting C# project to Android platform was not supported at the version 4.0. However, from the latter blogs I was unable to find further information about it.
I'm wondering how it's progressing now 😃

I do not know the progress, you’ll probably want to ask on the Godot community chat as the developers are more active there than on the forums, but last I knew Godot 4 still does not have Android support yet, as the releases after 4.0 so far have just been bug fixes.

In 4.1-dev1, the file mono/Godot_v4.1-dev1_mono_export_templates.tpz is still much smaller than the file Godot_v4.1-dev1_export_templates.tpz. That suggests that exporting a C# project to Android is still not supported.

The same applies to 4.0.3-rc1, and it would be strange if 4.0.3-rc1 had more features than 4.1-dev1, even though it was published later.

But you could download those files and see if the Android templates are present.

References:
https://downloads.tuxfamily.org/godotengine/4.0.3/rc1/
https://downloads.tuxfamily.org/godotengine/4.1/dev1/