I do want to address a common misconception here. People seem to be worried about the exposure needing to be raised (longer) as more and more of the sun is covered making the "whole sun" darker. That is not how it works. When shooting anything bright like the sun or the moon, the goal is not to overexpose the part you can see, but that part is always at 100% of its normal brightness. It's easier to talk about it in terms of the moon because you can test this yourself. The moon is very bright. To properly expose its surface I might shoot it at something like ISO 100 1/250th, F5.0 (give or take depending on camera). I use those exact same settings whether the moon is full, or just a sliver. If I shoot it any slower than that, then the part I can see will be overexposed.
What that means for the eclipse is that literally everything up to the onset of totality can be exposed using fixed exposure settings, and we do not need bracketing. But we do need to be able to manually fix those settings as the camera's own Auto mode might try changing the exposure as there is more dark and less bright in the same frame.
ZWO says they're working on manual exposures, so I think we're covered there.
Where we need bracketing is when we take the filter off, from just before full onset (the diamond ring) to just after as there's a lot going on in between, and we can't practice for it in any meaningful way. In my experience I don't think we need 10-20 stops. I was shooting 5-9 shot brackets in +/- 2/3rd stop increments. So at most 9 * 2/3 = 6 stops, and my darkest was too dark, and brightest was way too bright. After a few practice runs I was mostly sticking to 5-7 bracketed shots, and generally throwing away all but about 3 of those.
Can't say I really want to be forced to deal with RAW AVI as you need specialized tools to get useful stuff out of em and I think it would be really confusing if every frame is changing exposure. I'd be fine with JPG+FIT for each image.