macOS provide Emacs keybinding as a natively. At least, I need it on Visual Studio of Windows.
If you must get
Ctrl+A to be a keybinding that moves the cursor to the beginning of a line in Visual Studio, install Emacs emulation 2.
This post will make your wish come true.
How to setup
Extentions > Manage Extensions.
emacs in Search bar. Then, click
Download button. If it finished, Quit Visual Studio.
Windows show VSIX Installer. Take care of it.
Next, launch Visual Studio and Open someone project. So, appear Emacs emulation's dialog. Click OK on the one.
Tools > Options..., then select
Environment > Keyboard.
The installation maybe completed with the above. So please try
Ctrl + A on text editor in Visual Studio.