Kinda depends The parity has to be larger than your largest drive. but you can have it move data around between fast and slow drives as it is used. It can do pretty cool stuff with a few clicks. It amazes me every day.
Unraid. Mix and match drive sizes. Its magic
for ease of use i would not use a pci coral. usb just is easier. passing the usb through to a dock or vm is easier. i use unraid and it was extra work to get the pcie vs usb coral setup. I have a nuc with a bunch of ssds for this kinda thing too.
the cold is helpful but moving the heat, but is the hard thing getting it away from the space craft. Since there is no atmosphere to take away your heat it just kinda sits there. If it is getting the suns rays it can be even more difficult. so basically it is quite hard.