Hi Richard
Sounds like a few things going on.
You connect the SVBony into NINA's Camera tab, correct? When you say grainy, how grainy? NINA can show a stretched image, and you can control the stretching level yourself. Go to Options > Imaging and on the right under Image Options, click Advanced Settings and play around with the settings there. Also check the unlinked stretch
Do the same for your Canon camera (the debayering settings might be more helpful here) to show them as colour.
And just to be sure, you've loaded all the appropriate SVBony drivers as well?
https://www.svbony.com/Support/SoftWare-Driver/
In addition to the ASCOM platform, looks like you'll need both their ASCOM app and possibly the camera drivers as well