On a tangent: are there any data about nand data retention in low temperatures? Such as putting microsd in a freezer at -15°C ?

Whaaa? How much time? Does this also apply to SD cards and such?

Here's a link I found with a quick google search: https://www.minitool.com/partition-disk/what-happens-to-data...

According to this, JEDEC Solid State Technology Association's standard is that SSDs should be able to retain data for 1 year at 30C. Not great for an archival medium.

Here's a Quora discussion about it: https://www.quora.com/How-long-can-SSD-store-data-without-po...

Vendors will claim much better numbers than this, but the standard isn't very good.

It is also not at all clear what is needed to "top up" an offline SSD to assure the data is maintained. Some people say that merely connecting the drive to power for a few minutes to hours lets it restore the fading bits but others think nothing but a full rewrite of the data will. I haven't seen any official information or testing on this either so the conservative rewrite assumption seems the most reasonable.