Just stumbled over “Blokada”: blokada.org.
Aparrently (if I got it right) it keeps a big list of know ad- and tracker-Servers, and looks at all the DNS-Request from the phone, and just blocks all that are on the list.
They (say they are) financed via donations.
Blokada efficiently blocks ads, tracking and malware.
Found it via and took most of the info from this blog: