Pi-hole blocks ads served by these networks just fine. Never seen an ad in Boost for Lemmy or for Reddit, though I tend to use Jerboa now that I’ve gotten used to it while I was waiting for Boost for Lemmy to release.

DNS based adblocking like Pihole or Adguard limits you to receiving advertising hosted by the app provider (youtube for example) which is usually better curated than third party advertising networks and less commonly found at all.