LilyGo TTGO T-Wristband that turned up today, catchy name.
LilyGo are known for producing a lot of 'maker friendly' development boards where they cram a lot of useful stuff together on a board in various combinations, lots of it based around the ESP8266 or ESP32.
Chances are there's a combination that might not be exactly what you want, but close enough you don't need to build something up from scratch or a tangle of different modules. Want an E-paper display, OLED display, LORA radio, Cellular connectivity, LiPo charging circuit and ESP or some random combo of 2-3 of these on one board they probably make it. It's all cheap and cheerful AliExpress/Banggood fare and I've bought a few things from them over the years.
This here is closer to an actual product, it's a 'fitness band' looking much like one of the sea of cheap BLE ones available for attaching to your phone but it's maker friendly with a programming cable and apparently usable code for all the components on GitHub.
Based around the ESP32 it's probably not the best platform for something like this as it's too power hungry, but it should be something I can program myself.
I have plans to tie it into my mesh network and directly deliver messages over ESP-Now with no need for a phone.
This is a kind of speculative purchase, I may not find the time to get the code in order for when I need it, but it was cheap as chips and if it does work it will be great.
If it does work I may buy 2-3 more.