Hi and welcome to the group 
Glowforge will not read Inkscape Gradiant objects but you can turn them into pixel images and it will read those, Or you could play with Gimp that is also free and bring those images to Inkscape.
If you have a grayscale image where black is deepest and white is not cut at all and in between is in between that is how the Glowforge 3d works.
By either way, Flowers are a great thing to start with 
though you might not be able to stop with just one…
