Hello
Is it possible to transfer my Stremio content to Nuvio without having to search and selected all my movies and series content ?
As for transferring the content see the @ALegg post below 
Not a Stremio user so not sure Stremio supports a cloud based Tracking App like Trakt, MDBlist, or Simkl but if it does you could easily get your shows/movies synced with Nuvio because Nuvio supports those integrations
Yes. There is a free tool specifically built for this: NuvioSync.
What NuvioSync transfers
Library — movies and series you’ve added to My Library (it merges, deduplicates, and skips items already in Nuvio)
Watched status / history
Continue Watching progress
Supported addons (manifest URLs)
It does not require a Trakt account. Credentials are sent directly to the official Stremio and Nuvio APIs and are not stored by the tool.
Thank you @ALegg . I have learned something new today and have a new tool in my vault. Happy Friday the 13th and have a great weekend.