How do I hang vertical patio door blinds on drywall with a half in space behind it then a concrete wall. I cannot access the concrete directly to manipulate certain screws etc.
Here's what I would do.
Make a standoff spacer to bridge the space between the concrete and drywall surface. Make the spacer out of a piece of small PVC tube, or better, aluminum tube, say 3/8ths or 1/2" diameter at most, cut to match the distance from the concrete to the outside drywall surface.
Drill through the drywall into the concrete with a masonary drill to accept a Tapcon screw. Make sure the drilled hole is deep enough (maybe half an inch longer than the screw's reach) and work the bit in an out to clean as much dust as possible from the hole.
Enlarge the hole in the drywall to accept the spacer. Use something for a depth gauge that you can push in against the concrete and mark the drywall surface, pull it out and measure the distance, and cut the spacer to that length. Install the Tapcon through the bracket and spacer into the concrete.
This may not be ideal, or workable for some, but I've done this in many windows in a block home: Attach a 1x4 to the top inside of the window, using adhesive caulk and two tapcon screws. This gives me a wood surface that's much easier to screw into for hanging blinds. I caulked the slight gap between board and plaster wall and painted the board to match the wall.