@leocg Thanks for replying.
Opera One(version: 115.0.5322.68).
I have now enabled it in settings, which has allowed me to enable it in the sidebar.
Somehow I looked for it in settings several times without finding it.
Apologies and thanks.

I can't see the music player or video player on my sidebar or as an option to display on the sidebar.
Does some other option have to be turned on for these players to be options ?
NB I have updated to the latest version of Opera for Windows.