Was the F4F-1 Wildcat ever built?
According to aviation-history.com the design never left the drawing board.

In 1935, the US Navy ordered the XF4F-1 as a backup to the US Navy’s first monoplane fighter, the F2A-1 Brewster Buffalo. However, data from the Buffalo demonstrated that the biplane fighters could no longer match the performance of the monoplane. It was now apparent that biplane fighter's days were numbered as the XF4F-1 performed no better than the re-engined F3F.
The design never went further than the drawing board and the Navy’s thinking had finally reached the conclusion that the navy fighters were lagging far behind land-based fighters. The biplane design was scrapped in favor of a new prototype, designated the XF4F-2 (G-18).