A developer can mean two different things by “Flutter deep linking.” First identify the direction of the handoff.
When a user taps Contact us and your app opens a WhatsApp conversation, your application is launching an outbound link. DeeplinkX can construct supported provider actions and manage their available fallbacks. A general launcher such as url_launcher can also hand off URLs; your app then owns any app-specific URL construction and orchestration you add.
When a user taps a link in a browser or message and your own app opens a particular screen, that is an incoming link. Your application needs incoming-link delivery, platform association/configuration where applicable, and a route that interprets the URL. DeeplinkX is not a replacement for that configuration. Evaluate tools such as app_links and your existing router (for example go_router) for their documented incoming-link/routing roles.
One product can need both: handle a received event link in your own app, then launch directions to its venue in an external map app. Keep the inbound route and outbound action separate in your architecture and documentation.