SkyWalking native UI provides the default visualization solution. It provides observability related graphs about overview, service, service instance, endpoint, trace and alarm, including topology, dependency graph, heatmap, etc.
For most open source users, this UI solution should be good enough to use. And you have other open source options in visualization. See UI setup.
Also, we have already known, many of our users have integrated SkyWalking into their products. If you want to do that too, please use SkyWalking query protocol.