Can we render NetSuite pages via

iframe

inside a Suitelet? I want to list search results. It is working but issue is that filter dropdowns are not working.

Yes, assuming you don't run into cross domain issues, but if your on XXXXX.netuite.com and the iframe is also pointing to something on XXXXX.netsuite.com than you should be fine

The problem is that dropdowns does not work. I tried to render the search results page which rendered correctly but clicking on filters does nothing.