Looking at your debug log, everything seems to be properly configured. Your Pi-hole is listening on port 443 and use the automatically generated self-signed certificate. The only possible cause I cannot check right now would be firewall (e.g., iptables) blocking access to port 443.
How do the error messages look like in the other browsers you've tried? Maybe Safari simply isn't happy with the self-signed certificate? Maybe you need to add some exceptions somewhere (I am not familiar with Safari).