Would like to add members to a group based on the results of a Contact search, such as creating a group of all members who signed up “Master Wine Tasting” Event.
Contacts>Advance search>Registered for specific event(s) > select> “Master Wine Tasting”…a saved contact search is created (not a group).
As each member registers for the event, the saved contact search is automatically updated.

Saved searches are only good for emails and not events (membership level or member groups).

Seems to be a disconnect between contact search and groups. At no point can you use one or the other.
If WA added to “Events access permissions” > membership level, member groups and "saved contact search" all would be good. Then you could list events and send emails based on “saved contact search”