After execute the following command, you will get linux-headers-5.10.35-dirty_5.10.35-dirty-4_arm64.deb in folder flexbuild_lsdk2108/build/linux/kernel/arm64/LS/output.
$ flex-builder -c linux-deb -p LS
Please copy linux-headers-5.10.35-dirty_5.10.35-dirty-4_arm64.deb to the target board and execute the following command.
# dpkg -i linux-headers-5.10.35-dirty_5.10.35-dirty-4_arm64.deb
# cd /usr/src/linux-headers-5.10.35-dirty