The reason Tailscale gets recommended so often is because it (and VPNs in general) is the most secure ways to access your services remotely. It's also pretty easy to install and get running.
Nginx, on the other hand, is a completely different approach. To make lives a bit easier, let's take Nginx Proxy Manager instead of plain Nginx. Installing it is the easy part. The real work starts afterwards.
You’ll usually need a domain, set up a DNS token for the certificate DNS challenge, configure something to keep your public IP updated, and create and manage all your subdomains. And all of that just to make your services reachable from outside your network.
Once you’ve done that, your services are basically exposed to the entire internet. That means any device online can try to reach them. Because of that, you also need to put additional security measures in place to protect them from people trying to access or exploit them.
Therefore only expose what you absolutely need to expose.