I don't believe there is an option to change the RAW format on the camera, it outputs CR2 files which I've always known as Canon RAW.
With the external editors, I have one which does support the RAW file - Luminar. The problem is, when you goto the editor, it wont let you use RAW as the original, and therefor won't let you then use an external editor with it, only allowing you to send the JPEG to the editor. RAW only files it will not do anything with other than display the thumbnail of the image.
I like the idea of RAW to TIFF as an alternate workflow. There may not be that many images that I need RAW for anyway, I'm not a dedicated RAW shooter at the moment, just use them for challenging situations where I know I will need to do some post processing on them. I think for now I will stick with RAW+JPEG and leave them in Photos. If I need to do some post from the RAW I can just pull it out of the library manually. If it takes too long for Apple to support them, I might just bite the bullet and go to Lightroom.