I do most of my daily tasks with cell phone and tablet while on the go, not everyone knows modern cell phones and tablets are quite powerful, but I still want a real computer which is small enough for daily carry, that can handle what I will do with computer. Modern phone/tablet apps can do most but not every tasks we will do on a real computer, there are limitations. Currently I found the uConsole, which is running on a Raspberry Pi, with a full keyboard, great display, and supports 4G cellular, only that it relies on the unreliable microSD card, internal emmc is not well supported as system drive, and limited to 32GB, the unit is mainly for developers. I wonder if there's other option for me, and I will need the cellular connectivity, any comment ?

I don't understand. I have an RPi4 running without microSD card, with an usb "hard disk". Works very well.
You can find a lot of similar devices on the net, see for example here: https://www.seeedstudio.com/blog/202...uters-in-2020/

If not to be used 'on the go' - maybe a RPi5, small & light, can be fitted with an M2 drive via an adapter, connect to a TV, possibly with a folding or micro keyboard, but don't know if there is any cellular attachment available for it.

Subnotebook.

Thanks for the link, and I boot the Pi 4 via USB too The uConsole only has one USB port to use unlike the Pi 4, there's adapter to expand the ports but takes up the space for the 4G module, of course I can use external adapter