I have both the FNIRSI HS-01 and Kaiweets KETS02, they are identical hardware. I haven't done a side-by-side comparison or looked that closely but I don't recall any UX differences in the firmware so my guess is they're the same.
Hello, the Kaiweets KETS02 has a firmware update available whereas the HS-01 does not. Could we apply that update to the HS-01 if the hardware is really identical?
I should clarify -- when I say the hardware is identical, I mean in appearance and UX. I have not torn down either to compare internals. I would probably not risk upgrading the firmware from one to the other until I've heard someone else do it successfully, and who knows if the firmware tool will even allow you to.
That said, FNIRSI has an almost identically named firmware update that would imply they might be the same:
FNIRSI filename: HS01_V0.1.s19
KAIWEETS filename: KETS02 temperature calibration_V0.1.s19
However they are very different, with different file sizes as you can see in the comparison screenshot below. The FNIRSI version also dates from a year ago.