Sending the pihole admin password in a non-https url query string seems like a bad idea. You might argue that your network is 'trusted', but then I'd remind you that this pihole device is designed to intercept all dns on your network, and would be used quite maliciously if compromised.

You can add a certificate and then access it over https: https://discourse.pi-hole.net/t/enabling-https-for-your-pi-h...

I don't think my neighbors are sniffing my wifi traffic, I wouldn't think the password to be at risk