How to make gradient blur in Inkscape (or svg)?

Question

inkscape

Is it possible to make a blur in a vector along a gradient, respectively, of a vector object?

Both the solution in inkscape directly and in svg (in case there is no implementation in the specified editor) are welcome.
A separately blurred object with a gradient in transparency is not an option, as well as sophistication in the form of intermediate objects:

Answer 1

I found the answer while writing my own article.