Non send sync resources

[azriel91]

Attempt at #673 / get #674 to be tested.

Checklist

• [x] I've added tests for all code changes and additions (where applicable)
• [ ] I've added a demonstration of the new feature to one or more examples
• [ ] I've updated the book to reflect my changes
• [ ] Usage of new public items is shown in the API docs

API changes

[azriel91]

Bringing discussion back to #674.