This is cool, but if you switch in your Sidebar from "Open in Sidebar" to any other tab (e.g. "History"), then any playback running there stops.

Also it allows you to have only one instance of "Open in Sidebar"

Great that it has a "request mobile site" option, but what is really needed is a "Request Desktop site" option. Sites like airtable refuse to show a mobile site as they want us to get an app. On vivaldi I can tick show desktop which works.
I hope you can add this feature.

It works as it should work but 2 options are missing that I consider to be very important:

1- To be able to clone the main browser window to the sidebar without having to do it from the link, that is, from the contextual menu of the Web page
2- Allow the use of extensions (Ex .: translator) as if it were the main browser window. It is very annoying not to be able to use the translator in the sidebar :(