It's not only more complicated, it also does not sound to me like it would scale. What do you do when you have N servers? Do you buy N raspis, or do you keep using one bastion host? How do you automate it when you sooner or later must (re-)deploy?
If you set this up once ("this" meaning adding networking, SSH and tailscale inside initramfs), you can just do the same thing for the next server you set up, and you don't have to worry about the failure of one node affecting the other(s).
The approach I've outlined scales fine to N servers, it just doesn't work if they're on different networks.
But scaling also isn't really a parameter I (or the author) are optimizing for: we have a single beefy server we do all our work on, and a thin laptop client we want to access the server from, remotely and booting an encrypted root partition.
I don't necessarily understand the deployment question. If it's about the Raspberry Pi, I just do my updates when I don't need to use it to boot the server.
If you set this up once ("this" meaning adding networking, SSH and tailscale inside initramfs), you can just do the same thing for the next server you set up, and you don't have to worry about the failure of one node affecting the other(s).