As of June 30, 2019 Nintendo Switch has sold it a total of 36.87 million units. The figure, provided by Nintendo in its recent financial report for the first quarter of fiscal 2020, is also accompanied by console sales in the last quarter (from 1 April to 30 June 2019): 2.13 million units.
To make a comparison, in the same period PS4, a much older console, sold 3.2 million units. It should be noted that Nintendo Switch sales are traditionally weak in the first few months of the year, but are strongly accelerated over the Christmas period, when the strongest exclusives are usually launched.
Nintendo has not reduced the console's sales forecasts for the current fiscal year: 18 million units. So by March 31, 2020, Nintendo Switch sales are expected to reach 52.74 million units. Probably Nintendo is betting everything on the new models coming, namely Nintendo Switch Lite and the revision of the standard model.