I think it's about sata, not ata ... The last standard of sata is sata3 (750 MB/s)
In case of R5 it's not even SATA (CFast), but Canon skipped directly to PCI Express / NVME (CFexpress).
Oh yeah lol, I miss understood. However there are many examples doing CFexpress to SATA on YouTube. Shouldn't be a big deal.
Are you sure?
CFast to SATA do exists, as CFast uses SATA protocol. But
CFexpress is NVME (PCI Express), that's why I wonder if there will be similar trick possible.
But even if possible - probably a little harder due to PCIe signalling requirements.
By the way - there are three types of CFexpress cards - A, B, C. They differ in physical dimensions and number of PCIe lines. I can't find any information which one will be supported here, but I bet for type A, which is physically similar to SD card.