Is it possible to use an own icon for a script (no picture entity)?

Hi together,

I am searching for a solution for my frontend. I am using a button entity for a script, but I don’t find a way to change the icon to a personal one.

The .png file is saved in the www-folder.
The use of ‘icon: /local/symbol.png’ / ‘picture_entity: /local/symbol.png’ did not work?

Any suggestions?