It seems to be possible. I've found somebody who has done it here:
https://www.youtube.com/watch?v=etJovr7wQiI
It's connected to this post also:
viewtopic.php?f=8&t=42512&p=443641&hili ... al#p443641
I'm really grateul to sawer/bitsawer for their work here.
Unfortunately the github page doesn't have demos of the model in the video where there are shapekeys and bones like you would see in a 3d modelling program such as blender for example.
Generally I'm pretty decent at working with and understanding renpy, and I have a lot of experience with 3d modelling in blender. I would really like to be able to export a 3d model mesh that has some sort of bone/armature structure attached to the mesh for movement. It would be really useful to be able to use shapekey animation to adjust facial expressions.
I know alternatives would be to just use live2d, a movie clip, or use rendered frame by frame animation. In my experience these alternatives offer a lot of limitations and issues. Live2d is probably the best alternative, but is still more limited than using blender to create a rigged 2d skeletal animation. Not to mention the license thing and that it seems newer versions can't be used without internet connection. Movie clips and pre-rendered frame by frame animation are very inefficient and take up a lot of memory. They can be very tedious and time consuming to produce. If you for example, have a small mistake on the character or want to change a detail then you have to redo the whole movie clip(s) and re-render all the animations. It's not as practical as a 3d model where you can simply edit and update the textures quickly and easily to fix those kinds of issues. A low poly 3d model or rigged 2d skeletal animation made in a 3d modelling software will 9/10 be much less memory than a movie clip or loading potentially 1000s of images for a few short animations.
Any help with this at all would be really really great, thanks!