There's a book, Shrubs and Trees of the Southwest Uplands, that describes and ids plants in our region by their communities, including one on the pinon-juniper complex. That will give an idea of what "belongs" and you can search for analogs. Like rugosa
rose for the wild rose.
From the reading and old-timers I've talked to, my belief is that before the
cattle arrived, the
land in my area was much more heavily grassed. The descriptions of the Old Spanish Trail travelers describe 3' high grasses among the sagebrush. Wild potatoes. Camas and sego lily. What we are seeing now is the result of over grazing and water diversion. Going back to a pre-grazing reconstruction adds a lot of possibilities.
That said, getting from here to there is going to take water. Asking a man in these parts how much water you have is like asking how much money have you have in the bank, but what you can do really depends on how much water you can apply for establishment and maintenance. Consider the riparian zone plants, like service berry, Arizona walnut and scrub oak. Analogs to those might be
apple, walnut and a mast oak. But they will need some irrigation. I suspect they were much more common along minor draws and ephemeral surface water before the pioneers turned the cattle loose. I'm not talking about recreating a stream; it's actually quite dry on some banks where these things grow, but they are hitting the water table. Which is another question to figure out. We think ours is 6-8' in summer. All of our irrigation effort is going into driving
roots down to that resource. Anywhere a Russian olive is growing, I figure is sign of available water resources not too deep.
Have you seen the Groasis water pans? I haven't tried them yet, and I kind of doubt they would get us through the month of June, but I think they might help for the establishment phase to reduce the amount of tending. The other thing you want is to make your planting areas "lumpy" to capture drifting snow. A half ring of rock on the lee side of a plant will trap snow that will melt when the sun hits the rocks. Most of our plants are in shallow basins that slightly block wind and trap any blowing snow.
Haven't read it, but the reviews are good for
High and Dry: Gardening with Cold-Hardy Dryland Plants. Might be a good resource to get started.
As for pinions, I ordered a dozen piƱon seedlings from the
UIdaho nursery in Moscow. The seedlings were fantastic and are growing ridiculously well where I am getting a bit of water on them every couple weeks. Yeah, it will take forever, but someone will eat those nuts someday.
Do update your profile to give some more details on your elevation, etc. Now that the blessed monsoons have started, it might be possible to get some cover crop (vetch maybe?) going to add some organic material to your soil, but again, that depends on how much water you want to throw at the situation and how long you have until frost.