I spoke on the phone with a Koodo rep to explain this issue, and he said that he fixed it by adding VoLTE access (similar to what was done in this thread). While this did fix VoLTE, I am still having the exact same issue enabling Wi-Fi Calling.
Is there anything I can do on my end to fix this issue, or do I have to request another callback from Koodo to get this fixed?
Best answer by rikkster
IMS status messages:
IMS registration status: available, VoLTE: available, or
IMS registration status: unavailable
It appears that once IMS registration is correctly set up, both VoLTE and Wi-Fi calling are accessible.
Wifi calling on Pixel 3XL won't turn on - see the 'Solved' section
Your best option is to request another callback from Koodo to get this matter resolved.