Importing from Inkscape to Fusion 360 is easy, just go in Fusion to Insert > Insert SVG/Insert DXF. But raaahhrggghh, the scale is completely off!
To make them compatable with each other, you have to adjust 2 settings in Inkscape:
Open the Document Properties with Cntr + Shift + D. Put the Display Units from mm to px. Put in the box Scale, Scale-x to 1.0. Put the Display Units back from px to mm. The scale will automatically change, don't adjust it anymore. Give your drawing the right dimensions again.
Extra tip: You can also adjust the Page Size to your drawing size in Document Properties. In the box Costum Size click on “ + Resize page to content…” And then click on Resize page to drawing or selection.
Now you are almost there. If you would import your drawing in Fusion now, you'd be off by less than a millimeter.
Inkscape thinks that you want te size of all the pixels that you see, including the stroke lines. (For example, your drawing is 100 mm wide, you have selected a stroke width of 1 mm, your size is 101 mm).
To make Inskcape clear that you don't want that, go to: Edit > Preferences (or Cntr + Shift + P) > Click on Tools > Select Geometric Bounding Box
That should do it! Go ahead and import to Fusion 360.
Is the difference a factor of 1.0666666? Than your pixels are probably defined differently. Inkscape used to have 90 dots per inch (DPI), but changed it to 96. Fusion might still thing you are using the 90 DPI. You can change this by going to: Extensions > Document > 96 to 90 DPI.