[M95D]

Yes, PiHole is the most common, but malware can easily bypass that using shared domains, P2P or IP addresses directly.

Use a filtering proxy instead and no gateway / route to the internet.

[chupasaurus]

1) Dnsmasq, you don't need the whole PiHole for that.

2) You're advising security through obscurity instead of a network namespace + firewall.

[M95D]

Please explain #2. How is a filtering proxy security through obscurity?