Unify the Function App and staging slot Bicep declarations

Question

I have declared a Function App ('Microsoft.Web/sites@2023-01-01') and a staging slot for it ('Microsoft.Web/sites/slots@2023-01-01') and when I modify the definition of one of them I always forget to modify the second one. I'm trying to unify both of them into one declaration so that only one change is required in the Bicep file. It seems that only the core of the declaration which is the resource type is different in each case but it seems to be impossible for the resource type to be replaced with a variable:

Is there a way to get around this?