How to manage new ideas coming at late stages of PhD
I would say based on my opinions and experience that no-one cares about the Thesis.

The Thesis is a set of publications that must be about the same topic. Your publications will be the ones cited, not the Thesis. The Thesis will be only found somewhere in the university archives, while the publications will the visible part of your work you are evaluated upon.

Thus I think that the Thesis should be pushed to the finish line.

EDIT: The form of Thesis may vary, so it is noteworthy that especially in arts and humanities, the Thesis may be a coherent piece of work. Then the Thesis can be evaluated as a whole.