Setting the CanSearchPublic flag for the PortalQueryParameters doesn't seem to have an impact on the results:
<SPAN class="keyword token">var</SPAN> queryString <SPAN class="operator token">=</SPAN> <SPAN class="string token">"type:(\"web map\" NOT \"web mapping application\")"</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">var</SPAN> portalQuery <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">PortalQueryParameters</SPAN> <SPAN class="punctuation token">(</SPAN>queryString<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
portalQuery<SPAN class="punctuation token">.</SPAN>CanSearchPublic <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">false</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">var</SPAN> maps <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">await</SPAN> arcgisPortal<SPAN class="punctuation token">.</SPAN>FindItemsAsync <SPAN class="punctuation token">(</SPAN>portalQuery<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
ToastHelpers<SPAN class="punctuation token">.</SPAN>ShowInfo <SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Web Maps"</SPAN><SPAN class="punctuation token">,</SPAN> maps<SPAN class="punctuation token">.</SPAN>TotalResultsCount<SPAN class="punctuation token">.</SPAN>ToString <SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN><SPAN class="line-numbers-rows"><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN><SPAN></SPAN></SPAN>