I know that most of them wore British issued flight gear including Irvin’s and there are a few of those in the Wright Patterson Museum, but I don’t know if they had issued A2’s while they were in the Eagle Squadron in 1940.
No Eagle Squadron members wore A-2s whilst serving in the Eagle Squadrons. The simple reason for this is that they were in the RAF at that time and were issued and used British AM equipment. They did extensively use British flying kit from their Eagle days when in the 4th FG.
The only widespread use of A-2s at unit level in the RAF (or RAF administered) squadrons was with the Norwegian squadrons in the RAF and principally 331 and 332 Sqns. These men were issued A-2s during training at Little Norway in Canada through a procurement deal for flying kit which the Norwegian government in exile had brokered with the US government.