https://inkscape.org/~frmdstryr/%E2%98%85inkcut

Is this extension working with 1.0 and Silhouette Cameo cutters?

Another deprecated extension (worked for me in past 0.9x versions): https://github.com/fablabnbg/inkscape-silhouette/releases

I've been waiting for the v1.0 upgrade for Inkcut too. According to their website Inkcut should work for Silhouette Cameo. According to the the first link you sent they said pr June 2020 that upgrade for v1.0 was coming soon. Downloading and unpacking the extension reveal that all files are dated 14.08.2019 so then "soon" is not yet here. I am tempted to try the standalone application which seems updated by december 2020, but documentation on how to install this for windows is still pending. I do not have the skills to guess, I guess.

Yesterday I managed to cut with the inkscape-silhouette: https://github.com/fablabnbg/inkscape-silhouette/releases

worked perfectly!

forgot to say, I use GNU/Linux, cut with silhouette on Kubuntu

and not through an Inkscape extension?

no, you can install silhouette as a normal printer and use inkscape-silhouette: https://github.com/fablabnbg/inkscape-silhouette/releases