Why did Trezor never add any functionality to the microSD card available in both the Trezor Model T and Trezor Safe 5? Did they simply forget that this feature exists?
...
PSBT signatures (they didn’t even do that), among several other possibilities.
They didn't forget that such a feature exists and AFAICR they needed to address a few things first
[prerequisites] before working on adding the PSBT functionality to the SD card... In addition to that, @prusnak mentioned "
there are things with more priority on their list" and seeing that it's part of a section with "
No due date", it's safe to say that it's at the bottom of the pecking order
[unfortunately].
What they seem to be focusing on is increasing support for shitcoins.
This is probably the case with any HW brand that also offers universal firmware and I understand why you think that's their main focus, but it's worth mentioning that both of their latest devices support fewer coins
[especially Safe 3 (incomplete list at the bottom of my post)] and they recently started "
deprecating some of these coins".