I'm afraid our American cousins forgot about the 8x64mm Brenneke, true it came about in 1912 & like all in the 64mm stable was ahead of it time.
https://www.brenneke-ammunition.de/en/rifle-ammunition/choice-of-caliber/

8x64 ballistics - 848m/s or 2780 fps with 198gn bullet
https://www.brenneke-ammunition.de/en/rifle-ammunition/tig/

So really the 8-06 was a reinvention of the wheel or a case of parallel development!
They certainly had the right idea for sure.