Hi Justus-san,
We have just recently started researching Godot to develop ss plugin.
At this time, we have not yet determined if and when it will be released, but we will let you know when we have an update.
If you try to support it by yourselves, here is some information that might be helpful.
You may already know this though.
SDK (C++)
I think you can use the sspj loader, animator, and the logic just before rendering.
https://github.com/SpriteStudio/SpriteStudio6-SDK
SS6Player for CPP
C++ runtime library that handles and renders .ssfb2 binary data.
It was written by the same developer as SS6Player for Unity, so there are many similarities in the source code.
So, it may be easy to understand for those who are familiar with SS6Player for Unity.
https://github.com/SpriteStudio/SS6PlayerForCPP
We apologize that we only have Japanese-language documentation available for them.
Best regards,
Yoshiteru
SpriteStudio team.