Menards now has the WAGO push connectors in stock. Also checked with my electrical distributor and they are stocking them, another brand, possibly Ideal. Looks like the answer to the pigtailing aggravation using wire nuts on 12 gauge. The distributor says the pros have had good results and they are competitive with wire nuts in volume sales. Plan to use them soon and report any difficulties, as we have all seen backstab problems before.
Joe