If the module you need does not have too many new dependencies, you could try to manually add it to the current kernel build 4.19 (default build instructions : https://docs.modalai.com/voxl2-kernel-build-guide/). Some users have been successful at enabling or updating modules from a newer kernel version.
Also, we are working on enabling kernel 5.4 on VOXL2 (no ETA for release yet), but the functionality is currently very limited. If you wanted to test wireguard on kernel 5.4 I can check if we would be able to send you a system image for testing, but we would not yet support any SDK features at all at this point.
Alex