Kernel modules not found in final image

I'm trying to build an image for my router with additional kernel modules. I usually add them directly into the kernel from make kernel_menuconfig as <*>, but this time the kernel got too big to fit into the kernel partition, so i selected some of them as modules <M>. I expected to find all these modules in rom /lib/modules, but they are not there.
Is this the intended behaviour of OpenWrt buld system, or is there something wrong with my system?

Yes. You need to enable the kmod packages containing the desired *.ko files in the normal menuconfig. If you just enable modules in kernel_menuconfig they will get built but not be part of any package and thus do not end up in the final rootfs.

I feel the need to make this a feature request!

I see no drawbacks. The modules are there; a simple copy operation would include them in the rom. A user like me with a specific need would not be forced to write a new package for a module that probably very few people (if any) would use if package is published, which is, again, complicated.

I tried to modify ./include/ I added a find -name *.ko in the kernel build dir and copy all of them to rootfs. This does the job, but also includes all the kernel modules that were selected in make menuconfig, not just those from make kernel_menuconfig.

Is there any way to separate these? Is there any list of modules that were built by menuconfig, not kernel_menuconfig?
Thank you.