It's not an exaggeration to say that your game is one of the primary ones I keep tabs on when browsing this site. The progress you're showing off is pretty exciting.
On the topic of growth animations and sounds, since you seem well-versed in tinkering with the game's rendering, have you considered using a nice fresnel shader to give the giantess a gentle glow as she's growing? I always appreciate it giving a little extra visual oomph to the growth, especially if the viewpoint is moving around and changing the location of all the size-reference objects in the PoV (as is probably going to be happening a lot, since the player's hopefully not going to just stand in one place to watch the giantess grow when she gets bigger).
(In case it's not clear what I mean, basically, like using the fresnel node in Unity to give an object (in this case, the giantess) something like a glowing outline)