I am not sure how influential US kit was before the fall of France but it is potentially an interesting change.
Well, the M2 Light is a better light tank than the MkI or Mk II, and in some ways better than the Mk III, as far as reliability and armor went. Hitting power, for the 37mm was on par for the Mk III and the MG versions, the .50 was far better than the Mk I and similar to the MkII in firepower.
An interesting route not taken was there in 1939 with the T6 series, a turretless 37mm TD with 25mm armor all around, on a chassis similar to the M2, but shorter, with 1.5 VVSS bogie assemblies shared with a trailing rear idler. It used twin Buick engines ganged together, like the M5 later did with Cadillac engines. Its main goal was to be cheap, under $20,000, while having high mobility and the 37mm gun
Similar to the Renault ZT3, but twice the armor and horsepower