I think some topics have already been opened about that but they are dated or really incomplete in my opinion.
So I'm reopening one on the Affinity Twitter team's advice.
It would be great to implement an artboard feature in Affinity Photo to be able to create multiple formats in the same document, as in Designer, but allowing us to have a transparent background and to work in only one app.
This way we could choose to create a document with artboards in it or not (a feature available in Photoshop) or even to add them in an existing document.
Would be great for working on social media posts for example.