Yes, for example, syncing on a kernel panic could lead to data corruption (which is why we don’t do that). For the same reason REISUB is not recommended anymore: The default advice for a locked-up system should be SysRq B.

Try perhaps the solution in https://unix.stackexchange.com/questions/648084/docker-interface-tears-down-wifi-internet

Try removing all the superfluous default routes.

Argon2id (cryptsetup default) and Argon2i PBKDFs are not supported (GRUB bug #59409), only PBKDF2 is.

There is this patch, although I have not tested it myself. There is always cryptsetup luksAddKey --pbkdf pbkdf2.

GRUB works just fine with LUKS2 these days. There is no need to switch bootloaders.

This seems right and exactly the way I’ve set it up. On subvolid=5 I have subvolumes @ and @home, in /etc/fstab I mount / as subvol=@, and /home as subvol=@home.

Could you run sudo lshw -C network and post the output for the wireless interface?

But you can do this.

Memory safety would be the main advantage.