Why do some people think that they will announce the price tomorrow and that it will be available for pre-order right away?
PS5 was revealed by Cerny at the time, games were shown later and the price and launch date were only announced months later. PSVR2 was revealed in a similar way, first the specs, then some people could test the device with Horizon, then Sony announced the price and launch date months later. In my opinion they will obviously present the technology and the differences between the PS5 and the Pro at the technical presentation. Specs will also certainly be available via blog post and initial announcements as to which games the Pro supports and will be patched.
We will still see games that run on the Pro by the end of the month. Some will only be as trailers on the Playstation channel, then at the SoP and definitely at the TGS. I am also expecting Death Stranding 2 previews, which could be played on the Pro, in the next few days. I don't expect the price until marketing has started. If Sony announces the price straight away, many people who think the price is too high will not even look at what the Pro can do.