Did Canon ever release a camera with a vertical-framing grip that wasn't a 1, until the R3?
It's possible they wanted to release a pro body, and didn't feel they had the technology ready to release something called a 1 at that point. Remember Covid was a headache for everyone and screwed up everything in those times. So they decided to do like they did with the EOS-3 around 1999, make a tweeny between the two normal steps.
So it seems some are thinking the R3 was literally going to be labeled R1, then at the last second they realized it wouldn't stack up and ran up a lot of R3 badging and did a global search and replace in the documentation. I don't think anyone can disprove that, or prove that (no photo of a trash can full of R1 badges has shown up by now so such proof probably doesn't exist) but it's not the only possibility.
What's also a possibility is that they had something grander in mind for R1, that required things that they saw simply wouldn't be ready, perhaps AI-related. (The idea of figuring out which player is nearest a ball and focusing on that person for instance. Or are any cameras able to be shown "Trump" and know to focus on "Trump" or similar? Or the sensor they patented around 2020 that would have no rolling shutter, electronic ND and a mode to double DR.) (I still expect there are things about the coming R1 that are under-rumored because they're too hard to explain, like this.) (And the issue may have been their internal R&D, or perhaps, CPU from vendor that could actually run the software fast enough, etc.) Anyway, they might have realized in late 2020 that there was really no hope of getting their planned feature set complete, and therefore went back a half-step to R3 to make a camera that many pros would love. In other words, the R3 may not be a camera they were planning on calling an R1, but rather, a back-up plan if they couldn't get all the features they wanted for an R1.
