In the NO, is it still acceptable to do the Agnus Dei with “dona eis requiem” for all three, rather than “miserere nobis” and “dona nobis pacem”? I’ve only ever heard that done in the extraordinary form of the Mass.
I believe that would be entirely illicit, unfortunately.
In the Ordinary Form, the Agnus Dei is always the same. In the Extraordinary Form, “miserere nobis” becomes “dona eis requiem” and “dona nobis pacem” becomes “dona eis requiem sempiternam.”