First, very nice company and product, and great that you are truly open source Got 3 of your keys, initially the aim was only to do some testing, now moving more towards using in real life, very happy.
A few comments / questions:
Do you plan on releasing some upgraded keys in the future?
Could future keys be waterproof? For example I also bought a couple of OnlyKeys, I overall like yours better because truly open source and from Germany vs. US, but the OnlyKeys has the big advantage of looking more waterproof since the whole electronics is coated in some transparent epoxy that looks quite robust (I opened your keys, and it does not seem that the electronics and PCB are protected in any way). That would be a small thing to add that would make a big difference to me. Also, this would make it (even if only little) a bit harder to actually temper with the electronics.
Could some future key include some hardware buttons like the OnlyKey? That would be great, so that I do not need to type my pin on a computer I may or may not trust fully.