People are conditioned to think Search has to work online. This was true when Google was created. No one had the processing or memory available on their desktop to search an entire index of the "useful" web. Not anymore. How large is a "useful" index of the web today? And can it fit on your laptop? The answer is yes. Can the entire thing be queried fast? The answer is yes. As an example take the entire stackexchange…
Laptops generally come in 128GB or 256GB capacities. So we're talking roughly 20-50% of an average laptop's storage just to hold the search index for wikipedia alone.
Meaning it is not feasible to store a useful index of the web today on a laptop unless you want to dedicate that laptop to pretty much exclusively searching wikipedia's english content.
You're not searching that database in milliseconds on average laptop hardware, either, but you probably could get it to be "fast enough" for practical usages if you could somehow solve the harder parts like storage size, freshness, and indexing more than just wikipedia's english content.