It appears that Valve's regular event with Steam Next Fest has done a whole lot of good for developers, with plenty more wishlists and sales happening.
What is Steam Next Fest? Originally starting in the summer of 2020, it's pretty much free marketing for developers. Teams can put up a limited time demo and run livestreams and talks about their games. Nowadays we see Valve talk a lot more about behind the scenes info, and recently they published an update going over some details of the 2020 Steam Next Fest event.
From what Valve said developers saw a 421% jump in daily wishlists for about half of the participating games, around 45% saw a smaller increase and only 5% actually saw a decrease. What's also interesting is that Valve say the rate of wishlisting continued to be higher for the "majority" of the games involved once Steam Next Fest ended with the median game seeing about 15% higher daily wishlisting.
How about sales though? For games that actually released since the event, the median was about a 292% increase in wishlists converted to sales when "compared to converting wishlist additions made in the two weeks leading to Next Fest".
Good news all around then it appears, with Valve noting they "continued to see strong player interest" for later events with "the median number of wishlist additions has increased in the 2021 editions of the fest".
For developers who wish to be involved in the October 2021 edition of Steam Next Fest, they have until August 15 to submit their content to Valve.