Will turning on firewall in Mac OS have any impact on IoX/eisy ui?

The macOS firewall mainly filters incoming connections, so in most setups it won't block IoX/eisy from communicating with your devices on the local network. What tends to cause trouble is when the app isn't allowed to accept incoming traffic. If you notice the UI not responding, check System Settings > Network > Firewall and make sure the relevant process is set to allow incoming connections. Outbound traffic is generally permitted by default, so discovery and local access should still work fine.