I believe this is completely outside the realms of RAW as I don't know of any way for a PC to gain Undead Fortitude beside homebrew,
Undead Fortitude reads:
If damage reduces the creature to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the creature drops to 1 hit point instead.
and Wild Shape reads
You automatically revert if you fall unconscious, drop to 0 hit points, or die.
So with these two wordings, if you drop to 0 hit points while wildshaped, and since you retain any features from your race, while wildshaped, does that mean that Undead Fortitude could prevent a wildshaped druid from turning back into its non-beast form?