There are cheap USB<->PATA/SATA or USB<->NVME adapters out there that usually also come with 120v AC -> 3/5/12v DC PATA/SATA power supplies (and if the SATA SSDs only need 5v then some adapters might work with USB alone).

I use them for working with old unmounted hard drives or for cloning drives for family members before swapping them. But they would probably work for just supplying power too?

The one I use the most is an 18 year old Rosewill RCW-608.

I don't know if the firmware/controller would do what it needs to do with only power connected. I wonder if there's some way to use SMART value tracking to tell? Like if power on hours increments surely the controller was doing the things it needs to do?