I have never shot footage with my Canon R5 in the Craw format so I cannot give you a solid answer to your question. However, I have shot 8K Canon raw footage using the H. 265 format and the M1 iPad Pro handles that just fine. I suspect that Craw using Canon's IPB (H. 265) would be just fine. Canon has done a terrific job of releasing firmware updates for the Canon R5 that have added many new features including the ability to shoot with IPB and IPB Lite compression (H.265) which still afford excellent image quality and to my eyes are virtually indistinguishable from 8K Canon raw captured in the All-I format but with much much smaller file sizes. Furthermore, LumaFusion allowed me apply the proper LUT for Canon Log 3 to my 8K H. 265 footage and played it back with the LUT applied with no problems.
The M1 iPad Pro is a great companion for the Canon R5, but an even better (and cheaper) companion is the M1 MacBook Air. The latter has the advantage of allowing editing in Final Cut Pro and using Apple Prores which the M1 iPad Pro does not. For those who are not Final Cut Pro affectionadoes, the M1 MacBook Air also allows editing in daVinci Resolve which has just been updated with a powerful rendering engine that essentially brings Resolve even in terms of speed of rendering with Final Cut Pro. The M1 MacBook Air is just as portable, if not more so, than the M1 iPad Pro and affords greater battery life. The advantage to the iPad Pro vs. the M1 MacBook Air is the display. The 12.9 in. M1 iPad Pro has an excellent display that is fully capable of displaying HDR content as it is meant to be seen.
I hope I have not bored you with all of this. I just want you to realize the strengths and weaknesses of the M1 iPad Pro and tha tthe M1 MacBook Air is a far less expensive, and in some ways, more powerful alternative.
Tom