Row Keys in Datasets: JoinAcross row keys; Demoting or deleting row keys

Question

I want to combine two datasets that share row keys but have different column keys. Visually, this looks like a JoinAcross on the row keys to me, but the column of row keys doesn't appear to be named. Can I perform this combination as a JoinAcross, or does it require a different function?

Also, the row keys are sometimes cumbersome--is there a way to demote them to normal rows?

Example of desired dataset combination

I have two datasets:

dsA = {<|"keyA" -> <|"key1" -> "a", "key2" -> "b"|>,
    "keyB" -> <|"key1" -> "c", "key2" -> "d"|>|>} // Dataset;
dsB= {<|"keyA" -> <|"key3" -> "a", "key4" -> "b"|>,
    "keyB" -> <|"key3" -> "d", "key4" -> "f"|>|>} // Dataset;

I want the join these such that I get a third dataset:

dsNew ={<|"keyA" -> <|"key1" -> "a", "key2" -> "b", "key3" -> "a", 
     "key4" -> "b"|>,
   "keyB" -> <|"key1" -> "c", "key2" -> "d", "key3" -> "d", 
     "key4" -> "f"|>|>} // Dataset

I have tried JoinAcross[ dsA, dsB, Keys[dsA]], but this produces unclear errors.

Example of desired Key demotion

I have dsA again. I want to "demote" its row keys, such that I get:

{<|"RowKeys" -> "keyA", "key1" -> "a", "key2" -> "b"|>,
  <|"RowKeys" -> "keyB", "key1" -> "c", "key2" -> "d"|>} // Dataset

Answer 1

Join at level 3:

dsC = Join[dsA, dsB, 3]

For the second part of the question:

Apply[KeyValueMap[<|"RowKeys" -> #, #2|>&]] @ dsA 

Apply[KeyValueMap[<|"RowKeys" -> #, #2|>&]] @ dsC

Answer 2

    Merge[{Normal@dsA, Normal@dsB}, Join @@ # &] // Dataset