I don't really see the value in a full-computer experience (which seems to be what most cyberdecks try to do - badly) but I can see utility in "sidecar"-style hardware, which is more akin to a phone app but with a better experience because of custom hardware.
I have a bunch of Home Assistant controls using a variety of custom controls and cases.
I have a custom version of Seeed's ESPClaw (https://github.com/Seeed-Projects/espclaw - there are a lot of other ESP Claws too) with a case.
I'm working on a Tamgotchi-style mini-game device using ESP-NOW to connect with nearby devices.
Lots of other random projects at various stages of development.
One-shotted LVGL UI (which I think it a bit ugly).
A Bluetooth gateway has a flat battery so 2 temperature sensors aren't getting relayed.
This is a Guition ESP32-S3-4848S040 board with this case https://makerworld.com/en/models/2859961-guition-4-esp32-s3-...
About $25 in total I think.
Currently it's mostly a case of building them to solve specific problems, and I don't really have much else I need. This one controls my temperature and lighting for when I don't want to pick up my phone.
I have physical switches for most things too.