We were thinking about including ways to navigate between multipage app pages as part of the initial release of this feature, but we eventually decided to not do this in order to keep the scope down. We are aware that people would find this useful and may decide to build it in the future. Feel free to file a GitHub issue requesting the feature.
To get rid of the sidebar nav component showing all of an app’s pages, there’s a (hidden) ui.hideSidebarNav config option that you can set to true. Note that we chose to hide this by default as we thought it would be rarely used, but we may change its visibility in case we see it used frequently.