@lolmaus I don't think you can. The search suggestions made by Google when using their home page are based on many factors, like your IP/location, search history (if enabled) and others (cookies) to give you what it feels are "relevant" results.
When Vivaldi uses the address bar to create this list Google will also most likely base the returned results on IP/location but not sure what other factors it might use. I do think Vivaldi also sends cookies on search requests from the address bar/search field which is not good at all (might report that as a bug actually).
The limit of five results is I think hard-coded somewhere, don't think it can be changed. The reason is likely to not clutter the drop-down with too many results.
You can easily examine these results by using the DevTools and looking at network traffic when running the search URL in the address bar. The results will be returned in a standard format (JS array/JSON?) They will also contain more results than five.
For instance below are my results when using the Vivaldi built-in query. So pretty standard results, but Google clearly knows my location:
["test",["testosteron","teston","test corona","testosterone","testament","test microphone","test corona oslo","test elsykkel"]
From a local shell using curl and pretending to be Chrome, no cookies, but it still knows my location. Not sure how to account for the slightly different results from the above one:
["test",["teste for korona","testosteron","test corona","test elsykkel","teste seg for korona","teste korona oslo","test robotstøvsuger","test robotklipper"]
From a shell on machine located in the US:
["test",["testosterone","testing","test my internet speed","testicular torsion","testicuzzi","testimony","testicular cancer","testament"]
From a shell on a machine located in Germany:
["test",["teste dich","testosteron","testament","testerheld","testberichte","test mineralwasser","testo","testspiele bayern"]
Also note that by default, Vivaldi does not have a suggestions URL for Google, because it's not "approved" by them, so any search suggestions comes from the hack of "pretending" to be Chrome.
