is there any way to have a widget launch an app of my choice?

sorry since I'm sure this is possible, but I'm not good at these things.

If you want that the overall widget (where you touch in the widget) you need to go in the editor to touch in the bar

items

background

etc

touch

enter in touch, tick the more icon in the top right to add a new touch, choose open app, touch above and now you have all of your apps, choose your app, finished. If you are going to use in the entire widget, you need to erase the Open editor touch that is by default.

you can create a transparent shape and add the touch here. Always you need to erase the Open editor touch in the entire widget.