After that, I added a bunch of blocklists recommended on this site and reddit, and then added some common whitelists as well.
I restarted my computer and phone which are the devices I'm using to test. Mostly I'm going to sites I know have a lot of ads, and on my admin page for the pihole I see that I have new leases for these devices
Fyi, I'm somewhat tech savvy but completely new to using a pi
You should see if it has something like DNS rebind in the settings and disable that ...
OR see if it allows you to change the IPV4 DNS IP on the WAN side top the IP of the raspberry.
That is all good however the IPV6 setup is a little bit (tricky and more) advanced.
You need to specify the IPV6 DNS server in the Router to the IPV6 IP of the Pi and enable a more stable solution for IPV6 on the raspberry so that it does not change.
Quite a bit more complex though ... You can (and should) disable IPV6 support within your network as it has no real benefit within a LAN.