Gracious
Shyonna is a modern American creation, likely formed by combining the prefix 'Shy-' with the name Yonna or Shona. It is often interpreted as a variant of Shona, the Scots Gaelic form of Joan, which ultimately derives from the Hebrew name Yochanan meaning 'God is gracious'.
Less common today
Shyonna isn't in the latest US Top 1000. It last peaked at #9,352 in 2008.
US births per 5-year period, 1990βpresent (SSA data).