Cent features are almost complete..

[Lichtenshtein]

Thanks for your elaborate suggestion.
We are also preparing for redesign of sidebar panel.
What functionality do you most want to see in the sidebar panel?

Downloads, Mute all tabs and other icons (except menu button) not related to extensions can be moved from the extension panel to the sidebar. After the flag --force-fieldtrials=*ExtensionActionRedesign/Disabled became useless, with a lot of installed extensions there became too much icons on the extension panel. This way we can free up some space on it by moving the icons to the sidebar.

I myself would like to see the same thing as in competing browsers, I like how sidebar functions are implemented in them. The main ones are the history panel, the downloads panel, the bookmarks.

Of course I would like more functions: web-panels like in Vivaldi; Notes as in Vivaldi; RSS client as in Kinza; Quick access panel for extensions, where you can quickly turn them off/on; A sessions panel with a history of browser sessions; Something else ... Some of this functions already implemented as extensions for the sidebar in the Opera browser, so it's probably inadvisable to create these functions from scratch, it's easier to make support for installing extensions for the sidebar.