This. I think the technique is called the (monolith) strangulation pattern. WRT Agile, you need some tech debt stories to break open the monolith and set up fo

This. I think the technique is called the (monolith) strangulation pattern. WRT Agile, you need some tech debt stories to break open the monolith and set up for strangulation. Then some more stories to pull out a part of the monolith that is likely subject to the most product-driven feature evolution. Then, and only then, will you be able to entertain small feature increments from product owners. Tell them you'll need to earmark 20-30% of each sprint (or every 4th sprint) for tech debt / refactoring