You can even make it yourself.
Take a look at this fantastic Mainboard Terminal – a "full-feature PC powered by Framework's Mainboard" 3D-printed by Penk Chen. It has a 5" (1080x1080) round LCD and a fully 3D printable case. It is compatible with OLKB Preonic mechanical keyboard.
The computer runs Ubuntu 22.04 LTS and can run some programs, including the game Spacewar! It is held together by magnets, although the creator says you could add holes for screws.