That seems around what I’d expect the measurement error to be anyway

We have reactor designs that use already spent fuel, we just aren’t building them. We have enough spent fuel for centuries, and afterwards the reprocessed fuel is much less radioactive, and only for a few decades.

Recent controversy over an absurdly high failure rate.

https://www.theverge.com/22291828/sandisk-extreme-pro-portable-my-passport-failure-continued

Might be fixed now, but i wouldn’t gamble.

Your best bet is probably to make your own.

Find a high quality NVMe drive and put it in a USB enclosure.

If the USB ports or anything other than the drive fail, the data is easily recoverable.

Given your use case, buying an external drive is probably fine, just don’t get one from SanDisk.

Give it a decade and economies of scale, and maybe it will get it down to twice as expensive.