Kind of interesting how the improved Switch (staggered thru Aug) & Lite (Sept 20) both released in a 2 month window of each other just like PS4 Slim (Sept 15) & Pro (Nov 10) did back in 2016.
Did the improved Switch improve sales? I didn't think so looking at the numbers. They didn't even market it. I bet there are many more people that knew about the Wii U over the better battery Switch, and that is saying something. The PS4 pro, everyone and the mothers knew about. So those aren't really fairly comparable.
It did, at least in Japan.
From April 1-Aug 25 it averaged 42.5k/week.
The hybrid model has averaged 70k in the 4 weeks since the improved model launched.
As for the US, it's hard to tell but comparing the July to Aug drop from 2018 to 2019 might give us an idea.
July 2018-263k (Octopath #1, Captain Toad #14)
Aug 2018-203k (MH Generations #14)
July 2019-~250k (Fire Emblem #2, Marvel #4)
Aug 2019-~240k (Astral Chain #10)
Last year had a ~23k MoM drop while this year had a ~4% drop, and looking at YoY July was down ~5% while Aug was up ~18%.
Similar software performance from new titles so I think the MoM/YoY differences are due the improved model.