If the space will actually work for the equipment, here's what I would do.

Be sure the shelf that the equipment is going on is 3/4" thick. I'd insist on having a cabinetmaker make a shelf out of plywood, covered with melamine to match the rest of the closet.

Mount 1x2 (which in truth is 3/4" x 1-1/2") wood to the sides and the rear of the cabinet. The shelf will sit on this. Orient it so that 1-1/2" is the height.

Did I say the shelf will sit on this? NO. It won't. It will instead be mounted to it by driving screws down through the shelf and into the wood.

Under the shelf, I'd mount a piece of 1-1/2" x 1-1/2" angle iron (which in truth is 1-1/2" x 1-1/2"), prestressed so that it pushes up on the shelf.

Use glue and 3/4" flathead screws to mount the angle iron to the plywood shelf. (If you think flathead is a description of a style of screwdriver tip, well, it's not. It's the description of the shape of the head of the screw.) I mean the kind of screw head that's flush to the surface.

Just my thoughts on things.
Screw it all together.