@payard You can't set a specific shortcut for a custom site panel. However, at the URL opera://settings/keyboardShortcuts, you can set a shortcut for the "Show sidebar" command to toggle the showing of the sidebar. I like to set it to F4 as that's what old, Presto-based Opera used to use. But, you might want to use a different shortcut.
Chrome has this feature, Opera is actively stripping it out for some reason? It really sours my opinion of Opera that I can't customize my own search engine, like how dare you!?!?
Please, Opera devs, just stop disabling the feature from Chrome, there's literally negative work involved
@burnout426 Thank you mr Burnout. That is really not fair from Opera developper's team to enforce search engines. I even do not know whether or not this is conforming to European regulations. I thought Opera was a free software resulting from an open community of developpers. For France country we could argue that Google is not our local search engine but Qwant is. Then, I will think at using a true independant Internet browser (Firefox ?).