So if you look around on the internet, you can find instructions for alternative builds for Tahu and Kopaka that use parts from their associated Protector sets.
Apparently this model can be seen in the Mask of Creation app.
Kopaka Instructions (This link might not work. If it doesn’t, you can unlock the instructions by using the code, “ICE” on the Lego Club page.)
Onua also has an alternative build as seen here:
Unfortunately, nobody has found the instructions yet. Possible reasons;
1. Instructions are still unreleased
2. Nobody has discovered how to obtain the Instructions
Onua has a tail!