Export layers to files script but with 'trim' option ?

Yes if you use PNG-24 as suggested by GI87, then there is a Trim Layers option.

Another option is to select the layers in the layers panel. right click and Export As, which should Trim the layers.

Offhand, I don't know of any. I tend to make my own custom scripts rather than relying of other scripts. It's good to look at other scripts for how things are done. If you're new to scripting, start with doing simple things, then build on that. Using Scriptlistener is a good way to get code for many things. It's like recording an action that you can then modify and piece together other blocks of code.

I suppose you could create you own export script, perhaps cycling through the layers, turning the on the visibility for just that one layer, duplication the file with merge visible, then add the trim command in. Most all could be done using scriptlistener to get your general code.