Gist for my tutorial: Building a Gutenberg sidebar plugin Part 3: Registering with the block editor. https://vanaf1979.nl/building-a-gutenberg-sidebar-plugin-part-3-registering-with-the-block-editor/

metatags-sidebar-pluginsidebar.js

class Sidebar extends React.Component {
    
    ...
    
    render() {

        return (
            <Fragment>

                <PluginSidebarMoreMenuItem target="metatags-sidebar" icon='editor-customchar'>

                    {__("MetaTags", "metatags")}

                </PluginSidebarMoreMenuItem>

                <PluginSidebar name="metatags-sidebar" title={__("MetaTags", "metatags")} >

                    <div className="metabox-sidebar-content">

                        <h3>Metatags</h3>
                        
                    </div>

                </PluginSidebar>

            </Fragment>
        )

    }

}


export default Sidebar