Not directly, unfortunately. It does have the FBX that you can import into Blender and go from there, but no blender file is included in the zip file. However I can rectify this sometime if it'd be preferred!
Viewing post in Birdi VRChat Avatar (PC + Quest) comments
You would just need to make a new avatar project, import the unitypackage, and find the .fbx and textures to bring over to Blender. However, I've just added a Blender project so there shouldn't be any need for that!
As for sharing publicly, if it's about my models specifically (or any model someone is trying to sell for that matter) I ask that you please not do that and direct any interested parties to this page to purchase it for themselves.