You should ad "co-creation" already in the titles of the policy cycle's phases. [e.g., "co-implementation"...]

I'm not sure co-creation is the right approach. Citizens produce data when they interact with the public sector, they can be considered some kind of a by-product. It's not an active engagement. But they need to be aware and informed. Citizens produce these data because they have to fulfil some obligations or because they need something from public sector operators. Their focus is the specific operation and not the production of data. Furthermore, the use of big data in AI and machine learning usually goes very much beyond the perception of the citizen.

This can be discussed within a larger framework of collaborative policymaking and governance.

Data coming from citizens can be of great, but also of zero value. Campaigns letting them know of the potential value of their data should be realised. And they should even be reimbursed (e.g. small-scale tax reliefs?) when they contribute with actually valuable data. Direct co-creation might not be the most effective and efficient approach.