Manuals are live! 
Detailed guides on LUKS encryption, Cloudflare Tunnels (localhost-only), Redis, and Cron setup are now on Codeberg:
secure-nextcloud-install
secure-nextcloud-install - Here is instructions to assemble your self-hosted secure system
Codeberg.org (codeberg.org)

I've just finished documenting the whole setup. You can find the manuals for LUKS, Docker, Cloudflare, and backups here: