Personally I always felt that the film makes a clear implication that the power comes from the bond of the dyad.
The lifeforce of your bond… a dyad in the Force. A power like life itself. Unseen for generations. And now… the power of two restores the one, true Emperor.
(and then he drains their energy - nearly killing them - and restores his damaged body)
The only thing that confuses this is that Grogu has the power in the Mandalorian, but then you’re dealing with stuff outside the movie.
This is the first I’ve heard that the Force healing came from the dyad. It also seems like Palps can only use this power when they are together, which doesn’t explain Rey’s healing the snake.
If the intention was clear, it sure seems like a lot of people completely missed it.
JEDIT: This isn’t to say I dislike the idea. It’s pretty good, but it would make more sense if the life transfer power only worked to transfer life force from one member of the dyad to another (except for Palps warping it using his own power). The issue again is the snake, which argues that this is just a power that Rey has.