get https://api.similarweb.com/v1/website/{domain.com}/traffic-and-engagement/average-visit-duration
Returns the average desktop visit duration on a given domain (in seconds).
Price: 1 hit per request
Historical data goes back 37 months, depending on your subscription.
To retrieve 'Last 28 days', remove the start_date & end_date parameters from the URL and set granularity to daily or weekly.