Every ChromeOS device receives regular updates from Google until it reaches its Auto Update Expiration (AUE) date, based on component manufacturers. When a device reaches AUE, automatic software updates from Google will no longer be provided. Chrome devices last a long time. Therefore, before you buy one, you should check how long Google will release updates for it.
https://support.google.com/chrome/a/answer/6220366?hl=en#zippy=%2Casus
My current favorite Chromebox is the ASUS Chromebox 4. Its AUE is 2028. It also comes in 4 with faster CPU and memory. For basic use, the lowest Chromebox 4 with the Celeron CPU and 4GB of memory should be fine.
https://www.asus.com/displays-desktops/mini-pcs/chrome-os-devices/asus-chromebox-4
https://www.androidauthority.com/asus-chromebox-4-review-1219076
