I’ve tried to show a list of my tasks from the Obsidian-Tasks plugin or a Breadcrumbs tree view in my sidebar, but currently, there is just no way to do it. Other scenarios would be showing buttons or links from a certain document in a sidebar or referencing documentation from there.
Allow users to add document panes to the sidebar, the same way it’s been possible on desktop for a long time. On big devices like iPads, it may even be useful to allow the user to entirely switch to the desktop layout.
You can have a second pane open, but that will cover half of your screen at all times and is very suboptimal, especially with smaller screens.