Are units revealed exhausted?

Yes, units revealed from hidden enter the battlefield exhausted.

According to Rule 142.4, "Units enter the Board exhausted." Playing or revealing a unit from hidden follows the same rules as playing a unit from your hand. While a card is hidden, it does not have a ready or exhausted state; once it is revealed and enters play, it defaults to the exhausted state unless a specific card effect states otherwise.

As noted in RiftJudge FAQ #1908 and FAQ #6417, playing a card from hidden works the same as playing it from your hand, and the standard rule for units entering the board is that they enter exhausted.