Odoo-Modules/Work in Progress/fusion_backend_theme/static/src/webclient/webclient.js

import { patch } from '@web/core/utils/patch';

import { WebClient } from '@web/webclient/webclient';
import { Sidebar } from '@fusion_backend_theme/webclient/sidebar/sidebar';

patch(WebClient, {
    components: {
        ...WebClient.components,
        Sidebar,
    },
});