This is the spiritual successor of the Nokia N900, and it isn't a very good keyboard (but a better layout than N900). Its pretty much a rebrand of the same device with the same name from 2019 without the 'X'. Difference is it has better OS support (thanks to XDA, I guess), different SOC (recent SD600 series instead of SD835), and a different colour (blue instead of grey).
If you want a very good hardware keyboard use whatever BT or USB (such as HHKB) or try one of the Planet devices (Gemini/Cosmo/Astro). I own a Cosmo, the keyboard is superb. They all have the very same keyboard. Right now, I'd opt for an Astro instead of Cosmo. Also slider instead of candybar + horizontal flip, and a more recent SOC (D800), with a proven track record of keyboard.
https://www.indiegogo.com/projects/astro-slide-5g-transforme...
EDIT: and it has a backlight keyboard!
PS: Re, backlight: aye, it does (at least Cosmo/Astro, not sure Gemini), and you can put it lower/higher/off (I pref to have it on as low as possible). Even on Linux (Gemian / Debian for Cosmo). There's some minor bleeding, esp on side, but IMO not annoying.
There was next iteration called N950 which resembles this device even more. Sadly, it never shipped but I think Nokia shipped 100-200 prototypes to app devs before whole burning platform happened.