Unpacking a new base.txz snapshot:

doas chflags schg /etc/{rc.conf,pwd.db,group,passwd,master.passwd,dhclient.conf} && doas chflags noschg /lib/{libc.so.*,libcrypt.so.*,libthr.so.*} /libexec/ld-elf.so.1 /sbin/init /usr/bin/{passwd,chpass,crontab,login,opieinfo,opiepasswd,su} /usr/lib/librt.so.*
cd /
doas tar -xvf ~/base.txz
doas chflags noschg /etc/{rc.conf,pwd.db,group,passwd,master.passwd,dhclient.conf} && doas chflags schg /lib/{libc.so.*,libcrypt.so.*,libthr.so.*} /libexec/ld-elf.so.1 /sbin/init /usr/bin/{passwd,chpass,crontab,login,opieinfo,opiepasswd,su} /usr/lib/librt.so.*

Cross-building a new kernel for aarch64:

nice -n20 time make -j14 buildkernel KERNCONF=GENERIC-NODEBUG MACHINE=arm64 MACHINE_ARCH=aarch64 MACHINE_CPUARCH=aarch64

Sending to a remote machine:

scp /usr/obj/usr/src/arm64.aarch64/sys/GENERIC-NODEBUG/kernel example.lan:~
find /usr/obj/usr/src/arm64.aarch64/sys/GENERIC-NODEBUG -name '*.ko' -exec scp "{}" example.lan:~ ";"