Thanks for the tutorial, really useful and easy to follow! Just one problem I've encountered:
I've followed all your instructions to add a menu item and a toolbar button (which I've accomplished) but both the menu item and the toolbar button aren't responsive to clicking. Whenever I click on them I have no response from the program and it's like a useless button.
Also, one question:
How can I change the menu to be the Vector one instead of the Plugin?
Building a Processing Plugin (QGIS3) — QGIS Tutorials and Tips
https://www.qgistutorials.com/en/docs/3/processing_python_plugin.html