Welcome to the forum!
First, everything in the image is grouped, with several nested groups. Select the single group, and then click Object menu > Ungroup (or this button on the command bar
a few times. Keep watching the status bar (bottom of window, in the middle) while you do it. When the status bar says "No groups to ungroup" then you're finished.
Now you have the task of joining all the path segments into single paths. Well actually, the status bar identifies them as Lines.... Yeah, no, they don't have nodes, so probably you'll need to Ctrl A (select all) and then Path menu > Object to path, to make them paths. And then finally join the nodes.
Actually, you might not have to join the nodes. The machine might cut the path segments sequentially, and you can get by without joining nodes. Do you need instructions for joining the nodes?
Edit
Re-reading your message. I think you'll probably need to both convert to paths and join the nodes, for the best results with gcode.