I did a fresh install of Kali on RPi 4 using the 2022.1 image. Afterwards, I did a dist-upgrade, then apt install wireguard. It shows:

The following additional packages will be installed:
linux-image-5.16.0-kali7-rt-arm64 linux-image-rt-arm64

It seems like wireguard doesn't like kalipi-kernel package? wireguard shouldn't need a realtime kernel. The kernel install fails with:

update-initramfs: Generating /boot/initrd.img-5.16.0-kali7-rt-arm64
cryptsetup: ERROR: Couldn't resolve device /dev/root
cryptsetup: WARNING: Couldn't determine root device
zstd: error 25 : Write error : No space left on device (cannot write compressed block)
E: mkinitramfs failure zstd -q -9 -T0 25
update-initramfs: failed for /boot/initrd.img-5.16.0-kali7-rt-arm64 with 1.

Not sure about the /dev/root issue but seems like /boot is 59% full with one kernel installed and doesn't have space for a second.

wireguard should work with kalipi-kernel? Is there a way to install wirguard and have it ignore dependencies?