WordPress Requirements Update and New Gutenberg Optimized Attribute

I’m not quite sure if this is the place to discuss this matter (and seems like I’m late too, sorry) but as for widgets in themes I have 2 questions:

(1) Enhancing native widgets

There is a usecase that wasn’t taken in account, I think:
I tend to enhance WordPress native widgets with additional functionality. That requires unregistering a native widget and registering a new enhanced code instead. This is forwards and backwards compatible way though.
It was discussed in WordPress.org theme repo too:

So, are widget enhancements allowed by Envato too, or should all of these be a new widgets in a separate plugin?

(2) Functional widgets (with no content generation)

If a theme adds a custom search widget (for a Staff post type), should this also be added as a plugin? The widget produces no content at all, it’s just a functional widget providing better search options for dedicated post type.
Could these types of widgets be included with theme?

Thanks for any input on these!