How do coefficient of lift/drag variation with speed differs between swept and unswept wings?
It's not so simple.
For swept wings it is essential whether the leading edge is sub- or supersonic.
What does that mean?
If the leading edge is within the Mach cone emanating from the tip of the wing, it is called subsonic. The approaching air will &quot;sense&quot; what is coming and behave much like in subsonic flow. This avoids wave drag and keeps nose suction alive; an effect that can be maximized by the use of conical camber: Here, the leading edge is bent down similar to a cone surface with its apex at the wing root and the cambered part increasing towards the wing tip. This forward-facing part of the wing experiences suction which helps to pull the airplane forward.

Conical camber on the wing of the SR-71 (own work)
Of course, such a swept wing with a subsonic leading edge will also stall quite like it does at subsonic speed. However, the drag caused by a fully supersonic wing is so much higher that the small benefit of a higher lift coefficient does still not make it attractive. The drag at those high lift coefficients is so high that any airplane will quickly decelerate to subsonic speed once it tries to reach those lift coefficients.