For raw HTML in inline context, you can generate a custom role based on the "raw" role:

.. role:: HTML(raw)
   :format: html

and use it like

你\ :HTML:`<ruby>好<rt>hǎo</rt></ruby>`\ 呀！

The backslash-escaped spaces are required so that the inline markup is recognized. (Alternatively, set the character-level-inline-markup configuration setting to True.)