Those keys are almost certainly going to be revoked/refunded. I can't believe anyone would try to flip these instead of redeeming and appreciating a potentially great deal.
I'm not even that far on the anti-DRM side, but a forced Steam update adding DRM to a game you've already bought is ridiculous. I think with GoG and Epic you can turn off auto-updates.
It seems like you wouldn't get a great value playing super long (and cheap to buy) RPGs on a subscription service. Wouldn't you want to play through as many games as possible?
This is a deliberately cumbersome and worse solution. It's an all or none sort of backup. When you restore the backup it wipes out every PS5 game save on the console and replaces it with the backup. Contrast that to the PS4 saves where you can pick and choose which save you backup and restore...