Few days ago I saw one interesting open source device called WiPhone, but wait before you say anything, this is not the regular phone that uses sim cards for calling.
This is modular ESP32 device minimal phone that can make high quality free calls using WiFi and VoIP, and price is very affordable in my opinion ($89 - $139).
WiPhone can be used as walkie-talkie if someone makes a software for this, but I am much more interested in using it as hardware wallet.
This can be modified to work with MicroPython code (Krux DIY wallet is using it), that would make it very similar to Passport hardware wallet.
Great thing about WiPhone is that you can open it easy, repair and change any components you want.
Using this as a hardware wallet I would remove or disable wifi functionality, and maybe think about installing camera for QR codes.
First issue I have with WiPhone is they are located in Hong Kong and there might be some delays with shipping to other parts of the world.
Second thing I noticed is the fact they are still using micro USB for charging and firmware updates, it would be much better if they switched to usb type-c connector.
There is no encryption currently, but developers are open on adding this in future.
Note that developers still didn't release code in public.
Specifications:4MB PSRAM
16MB Flash
ESP32 Dual core running at 240 MHz
3.5mm audio jack
microSD slot
Size: 120mm x 50mm x 12.5mm
Weight: 80g
700 mAh Battery, 8 hours talk/1 week standby time
MicroPython for user applications
https://www.wiphone.io/