How to open a folder in Finder by a single mouse click? (using Icon view)

I agree with you on double click. I bought a multi-key mouse. I assign a key to double click. Not a perfect or free solution, but better.

This is not possible natively in macOS

While you may be able to assign a double click mouse action or a keyboard shortcut (CommandO) to your mouse but using something like AppleScript (i.e this answer and this answer) or USB Overdrive there is one main obstacle that must be overcome - the lack of hover to select.

However, there is an App called DwellClick which is designed to automate your mouse clicking for you. They have a feature called "point to click" which will select an item if you leave your pointer on it for a specified amount of time. After which you can click with a reassigned mouse button to emulate double click.