What hardware do I need to record 4-5 cameras at 4k simultaneously?

With the ATEM Extreme Iso I can record 8 tracks at 1080 simultaneously, which works quite well. I use it to create multicam videos with Resolve.

I would like to record at least 4-5 cameras in 4K simultaneously. In mimo I can record each camera separately.

What I don’t know at the moment is which Mac hardware I need for this or whether I should then fall back on 4K recorders from Aja. I would then like to make multicam edits from the recorded data. What I don’t know is whether it’s better to get a Mac Pro (if it can do that in terms of performance) or an additional device? Thanks