Hi,
As I recall, there was a code on this site that would switch to the Soften brush only while the Shift key was held down.
However, that code had a problem that it would not switch back from the Soften brush if the click was released at a later time.
Here is the code (included in the add-on) that solved the problem.
I tried to reply in that thread but couldn’t find it so I made a new thread.
Also, the default behavior is that pressing Ctrl switches to subcolor, but you can customize it to instantly switch to EraseAlpha with the press of a button from the custom pie menu.
I am wondering why these features are not included in the built-ins.