Perhaps there are fleeting clues which can be perceived through a dream, which illustrate or illumine the path to enlightenment. But then, I’d think such a clue, such a view into the essence of enlightenment, during the woken stage would be challenged greatly by our intellect. (our quest for practicality.)
Buddha, whether much or little is truth, had to be an extraordinarily focused, clear-thinking and very highly perceptive and intuitive human being, to have been able to discern from a dream, the path to enlightenment.
The training of a mind towards achieving enlightenment, is an arduous, dedicated practice/quest.
Much is written after the fact of extraordinary individuals having lived, having been.
What may be said now as to Buddha, Christ etc, is to be very highly scrutinized for purposes of authenticity, above all, practicality.
Who can truly say that Buddha through a dream realized the path to enlightenment?
That could have been added by his later followers, in order to give more merit to the Buddha and his philosophy.
And, let us say the Buddha did have this dream of what enlightenment would be, what path would lead to it…there would still be much ACTUAL work to be practiced before that image in the dream were to become truth. Utilized.
Enlightenment is the result of MUCH spiritual work, not just something gathered as, (one would grasp a soap bubble from the air) and have it become solid, permanently tangible.