That's how mine is set up and it works so far so go ahead and do it if you haven't yet, unless you got a reply from a someone saying that would cause an issue that I haven't spotted yet. The only issue that I think this setup can have is if lancache will only serve cached content to a dns request by the same ip (pihole) after a certain cooldown to prevent accidentally DOS attacking yourself in the case of accidentally making a dns loop or similar issue.
I wanted the lancache to use for WSUS for all computers since my home internet bandwidth is 6Mbps but not everyone in my house wa