I think the slide left/right for sidebar is a nice UX, as long as the user knows about it, and as long as you don't go beyond 1 main + 2 sidebars.
Discord mobile app used to have it for both left and right sidebars, and then a while ago someone had a brilliant idea that the "slide to reply" gesture was more important than navigating the app, and now you have to click a tiny ambiguous button to see the right sidebar.
Discord mobile app used to have it for both left and right sidebars, and then a while ago someone had a brilliant idea that the "slide to reply" gesture was more important than navigating the app, and now you have to click a tiny ambiguous button to see the right sidebar.