Regarding suppliers in general, we stick with the ones that do good work for us, and we look for new ones in areas where we are not satisfied. I think the only real way to evaluate a supplier is to run a batch of parts through them and see the output and of course see how they respond to feedback and iterate.
I know you told us there are no plans for making new devices in near future, but one of my suggestions would be to consider making Passport waterproof or water resistant device.
This probably needs a lot of work in redesign of inside, but even cheaper solutions like waterproof cases for protection would be interesting, and you could sell them separately.
I already know several hardware wallets that started making waterproof devices, so better think about that on time.
I generally like and support the idea of Passport accessories. Consumers can 'freshen up' the look and feel of their device, can improve, better protect or even fix it (Spare parts? Replacement screen? Replacement Keypad? Is something like this an option? Would it be compatible with your security model? What about right to repair?), while the company can keep selling stuff, without pushing out a new hardware wallet every year, making last-gen owners feel left behind.
I've tried to see if it is hard to open the device (e.g. for repairs) and while there seems to be no glue, it fits together very tightly and I was worried about damaging it. But accessories could definitely be purely external; like back shells, screen protectors, silicone cases, carry cases, waterproof cases, ... Although that may demand much more effort than what we expect.