pruned nodes sucks, you should buy a bananapi with sata port.
I don't understand your point. The performance of the raspberry and banana are similar and I don't think the disk speed will make much difference (except for the initial sync).
It is bettere to use a pc for initial sync, and move your copy of the blockchain on the bananapi later.
Initial synchronization on a raspberrypi will take some years.
Good suggestion, thank you.