The Seagate Expansion is made as an external drive by Seagate itself, so it was not put in some random enclosure.

If Seagate has chosen in 2025 to use some archaic bridge that does not pass the SMART commands, it is on them. That would be even more stupid than not implementing SMART in the HDD firmware.

As I have said, the previous external Seagate that I had bought in 2024 had SMART that worked fine over USB. I have a large number of external HDDs, most from WD. Some have been packaged by the HDD vendor as USB drives, others I have assembled myself into enclosures with SATA-to-USB bridges.

On all of them SMART works perfectly, except in this Seagate Expansion Desktop, where the drive replies that SMART is not supported.

Whenever I buy a HDD, I first run the long SMART self-test, to determine whether it can be used safely or I should return it immediately, even if the long self-test takes a couple of days on modern over 20 TB HDDs.

I started to use this procedure after I had some problems with a batch of WD drives, 2 decades ago, where all the drives had very frequent errors since the first few days of use. After running the SMART self-tests, which all failed, the seller could not deny an immediate replacement.