Installed this machine as I describe in my blog post: https://michael.stapelberg.ch/posts/2025-06-01-nixos-installation-declarative/
(But this time, I let nixos-anywhere reboot the Hetzner rescue system into a #NixOS installer with kexec, which worked flawlessly.)
The trickiest part was my unusual disk config: I need the space of both disks (at the expense of the RAID-1 safety), so I configure an LVM RAID-0. I used to put the /boot partition into a RAID-0, but systemd-boot does not support that, so a single EFI /boot it is.