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.)