I’d like to define what “usable” means. Let’s look at the Scrum Guide 2020:
“Developers are the people in the Scrum Team that are committed to creating any aspect of a usable Increment each Sprint.”
“In order to provide value, the Increment must be usable.”
Creating standard CI/CD or working on a database is almost certainly not enough. But in my opinion, sometimes it can make sense to work on internal value, which is useful internally. This is when you can use an Increment to lower the risk and deal with complexity by validating a hypothesis. For example, if the greatest complexity is in technology, I can imagine that a technical Spike may be a valid Sprint Goal. After all, what will be the value of the product if the technical assumptions turn out to be wrong?
We are dealing with complexity, which has many different dimensions. Customer’s needs and expectations are only one of them. Each Sprint should give you an opportunity to learn something new, to close a feedback loop. This is what empiricism is, isn’t it?