You can find list of DNS resolvers here.
You can also run your own resolver with Unbound, very easy to setup (only port has to be changed when used with Pi-hole).
You may also want to use DNS-over-TLS with Knot Resolver and Unbound.
More lists can be found from filterlists.com.
Use Blokada.
Not available on Google Play Store due to their Terms of Service.