Similarweb website traffic -- reduced coverage?

Hi I am a new Dewey user and I am looking to use Similarweb's website traffic data through Dewey. However, after downloading the dataset, the coverage seems to be smaller than anticipated. I have two questions on this: (1) though the time coverage on the main page is Oct 17, 2022—Jul 01, 2025, I see in the support doc that historical data goes back to 2019. is there a way to retrieve data prior to Oct 2022? (2) more importantly, I see about 8,000 unique websites in the downloaded data. I had thought that Similarweb's coverage of websites was much broader. Is there a specific way to download the data (or API call) that gets the broader set of websites?

Thanks very much in advance for your insights..!