I think things are pretty good with nixos-anywhere[1] now. I made a video last month walking through the process of provisioning a VPS on Hetzner Cloud[2] if you want to see what the process looks like in real-time.
I've never heard of kexec before; not very familiar why installing NixOS using kexec is only supported on x86 but not aarch64.
I wonder what are the advantages and downsides of nixos-anywhere v.s. nixos-infect.