Are app-only routers like eero a dealbreaker for advanced users?

For tinkerers, sometimes. Specialist subreddits flag that eero and some TP-Link Deco systems lock advanced settings behind a simplified app and, in eero's case, some features behind a subscription. Reviewers who want deep VPN, firewall, or QoS control tend to prefer ASUS or TP-Link's Archer line with fuller web interfaces.