FYI, here is a list of the top 30 games this week from Famitsu.
In the top 30, you get this distribution of games:
NSW - 20
PS4 - 9
3DS - 1
If you break them down by first and third party, then it looks like this:
NSW, 1st - 11
NSW, 3rd - 9
PS4, 1st - 2
PS4, 3rd - 7
3DS, 1st - 1
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.
Going forward, Switch install base is going to shoot far ahead of PS4 in Japan. Why wouldn't Japanese companies want their games on the Switch? Of course they would! There should be no reason to doubt. Over the next few years expect 90%+ of Japanese games to get a version on the Switch. Switch is by far the dominant platform and third party games are already selling well.