Some really superlative aircraft just barely missed seeing combat in WWII. The Tempest MK.II, P-51H, F8F-1 and F7F among the Allied types.
For example, a handful of F7F-2N night fighters were working up on Okinawa in August of 1945. On August 12, one Marine F7F-2N and an Army P-61 were vectored to a boogie detected on radar. The Tigercat arrived in the area first, but the boogie had reversed course and disappeared from the radar. It was not detected again. That was as close to combat as the F7F got to during the war.
P-51H fighters were flying routine patrols out of Iwo Jima, basically to familiarize pilots with the new fighter. There were no encounters with Japanese aircraft before the surrender.
F8F-1 Bearcats were aboard a carrier that arrived off the coast of Japan only days after Japan quit...
So close, yet no combat for all of the above.