All the Ribbon framework usage examples I've met so far require a Ribbon markup to be created and complited with uicc. I wonder whether it is possible to build a Ribbon control manually by adding it and its contents in a code (C, C++, C#).
No, not with Windows Ribbon Framework. To quote the docs:
To initialize the Ribbon successfully, a compiled Ribbon markup file must be available as a resource. This markup file is an integral component of the Ribbon framework; it specifies the controls to use and their layout.
To generate the ribbon programmatically, you would have to go with a different library, like DevExpress or FluentRibbon.