Correct me if I'm wrong, but I believe DietPi isn't maintaining the necessary kernel forks many of the devices require, and is dependent on upstream kernel fork changes from manufacturers/vendors.

Most of those boards can run mainline Linux, but certain features and integrations only exist in external forks that weren't put into vanilla Linux.

The end result is either that you're still dependent on someone maintaining bespoke Linux kernel forks in perpetuity, or you ship relatively up-to-date kernels that lack features, drivers, etc that only exist in the forks.