How can i use self compiled kernel module

The core devs decided to sign the kernel and to do it the way Michael posted above.
If you want support for specific hardware by kernel modules, these must be integrated into the system.
The signing is active now for some time. Why didn’t you ask for the kernel support of your device since then?

It has nothing to do with telling you, what is good for you. It is just a design decision like using the LFS model.