I used an ubuntu docker container for the build process
docker run -it -v $(pwd):/root ubuntu:groovy /bin/bash
Inside the container
apt update
apt install rsync dwarves bc kmod cpio flex cpio libncurses5-dev libssl-dev gcc-aarch64-linux-gnu bison kernel-wedge build-essential wget fakeroot git
cd /root
git clone https://git.launchpad.net/~ubuntu-kernel-test/ubuntu/+source/linux/+git/mainline-crack
cd mainline-crack
wget https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.7.6/crack.bundle
git bundle unbundle crack.bundle
git checkout 68a395e93c3ae2165136f437ce5210f32b6d9dd9
fakeroot debian/rules clean
dpkg-buildpackage -uc -ui -aarm64 -b -d
.deb files are found in /root afterwards. I am not sure if you really need all the dependencies.