If you plan to put it in a secure enclosure, I think it could be usable for a couple of girls.
I'd make a door from heavy canvas, or maybe even heavy rubber (like used for mud flaps on trucks) that can be opened upwards and secured to a hook or something for the daytime.
There's not much room for food or water in there, so I'd use an automatic waterer bolted to the interior wall. These can be fitted to hook to a garden hose if you are not great with plumbing.
I'd also cut out an area of the roof and insert a pvc feeder that can be filled from the outside. (Think large diameter pvc pipe with a 'U' shaped fitting attached to the end and a cap on the top.)
I'd drill holes in the walls to fit a 2x2 or 2x4 through for a perch. I doubt a nest box would be necessary in such a small space, but a smallish plastic container could be used for such. Maybe set one atop a cinder block inside the igloo.
I'd also provide (outside the igloo) a shady place for the girls to hang out- it'll get awful hot in that thing.
Again, this is assuming that the igloo is enclosed in a secure place and only a couple of birds will reside in it.
Let us know what you decide to do. I'd love to see a finished product.