The Chuwi RZBOX measures just 19.15 x 19.15 x 6.09 mm, and yet it contains an AMD Ryzen 9 4900H, a 45 W APU. The RZBOX will start at about US$500 and will be available with 16 GB of RAM with 512 GB of storage.
https://www.notebookcheck.net/Chuwi-RZBOX-revealed-with-an-AMD-Ryzen-9-4900H-in-a-tiny-case.559382.0.html