Would be great to include the new Microsoft Search API into SharePoint REST v2.0 endpoint like https://tenant.sharepoint.com/_api/v2.0/search/query
https://docs.microsoft.com/en-us/graph/search-concept-overview
https://docs.microsoft.com/en-us/sharepoint/dev/apis/sharepoint-rest-graph
This way SPFX would get straight access to the API without having to request extra azure app permissions.