How can I make this effect on Inkscape?
I feel lost because no sample seems to satisfy my needs.
Thanks for your attention and looking forward to your wonderful ideas.
If you want to output this as an SVG, there are a couple of problems.
Inkscape (and the SVG format) doesn’t support conical gradients, or gradients along a stroke. Inkscape does have a gradient mesh which you could use to fake a conical gradient (see Tutorial here), but gradient meshes aren’t supported in SVGs yet. Maybe it will be possible in some later SVG 2.x version, but it’s not possible at the moment, and browsers can’t display an SVG with a gradient mesh.
A possible work around
If you create a gradient mesh in Inkscape, you could rasterize it using Edit > Make a bitmap copy, then put it in a clipping path.
Here’s the SVG example (made in Inkscape)