In the latest Nightly version, the ability to automatically assign altitudes to all points has been added with the addition of a new Tools button in the Path panel.
0003890: [Хотелка] При редактировании пути (трека) добавить возможность автоматически прописать высоты всем точкам (zed)
This can also be applied to newly drawn paths, after the "Tools - Replace altitude with DEM data" command, the exported GPX file will also contain elevation data at each point.
In practice, it meets my request.
Many thanks to Zed!
Now I'm asking if anyone is able to fulfill this additional request
Add an option to the path properties to allow modifying the display style of the path line.
https://www.sasgis.org/mantis/view.php?id=3744