Yes and no. While Google will backport security fixes, and change the Chrome related layer, the kernel version you are running is likely the very same one your Chromebook shipped with.

This is why they can claim that anything shipped from 2017 onwards will support Android apps, but maintain a list of potential devices from before that. Because said support need various container related features only found in newer kernels to work.

Effectively Google has further masked but not really fixed the issues that makes major updates to Android devices such a hassle.