FYI, here is a list of the top 30 games this week from Famitsu.
NSW - 20
If you break them down by first and third party, then it looks like this:
NSW, 1st - 11
There are 9 Switch third party games in the top 30, while the PS4 only has 7. That means that third party companies are better off releasing their games on the Switch right now. Some might be Switch exclusives and some might get a release on both Switch and PS4. Either way, these third party companies are benefiting from releasing on Switch right now. I say this because the install base for PS4 and Switch are roughly the same in Japan and there are 11 Switch first party games on the list. In spite of all of this, there are still more Switch third party titles on the list than PS4 third party titles.
Well I mean a sales comparison makes a bit more sense. I will do a quick one. All figures are rough estimates and may include minor errors.
2017 Switch MC 500
81% Nintendo 5.9m 19% Other 1.4m = 7.3m
2018 Switch Famitsu 100
79% Nintendo 16.6m 21% Other 4.3m = 20.9m
1st half 2019 Switch Famitsu 100
68% Nintendo 3.5m 32% Other 1.6m= 5.1m
2017 PS4 MC 500
17% Sony 1.7m (including CoD and Minecraft figures...) 83% Other 8.3m = 10.0m
2018 PS4 famitsu 100
14% Sony 1.0m (including CoD and Minecraft figures...) 86% Other 6.3m = 7.3m
1st half 2019 PS4 famitsu 100
11% Sony 430k (including CoD) 89% Other 3.56m = 4m
More notes: via hiska-kun
PS4 - 43 third party games of 47, which 32 of them were new releases
NSW - 28 third party games of 47, which 14 of them were new releases
While it may seem Sony has a decent chunk of the pie, it is only because they publish Minecraft and CoD in Japan. Nintendo on the other hand does not publish Minecraft so it is not included in their first party sales automatically. The PS4 is still selling more than double the 3rd party games as the Switch despite the equal/lower install base.
On another note, so far in Japan for Switch, 3rd party games have only sold 7.3m copies in 2 years and some months (8.3m install base), making it a less than 1 third party game per console attach ratio. But of course we are missing quite a few games due to Media Create quitting.
The 1st half of 2019 doesn't really show a trend since everyone knows that Pokemon is coming out in the 2nd half of 2019 to keep the ratio close to 80% with Nintendo. Hopefully the 3rd parties can match the year before or exceed it.