First-party/Third-party software split depends on a per-platform basis (how much third-party support a console receives).
In Japan looking at the packaged software sales in the annual top 1000 by Media Create since the mid-'00s, it could be generalized saying that SCE/SIE's first-party software tends to be around 10% whereas Nintendo's first-party (Nintendo+Pokemon Co) software has usually the majority of the sales.
First-party/Third-party packaged software split in Japan for specific platforms:
NDS (miss 2004 and 2005)
First-party: 52%
Third-party: 48%
PSP (miss 2004 and 2005)
First-party: 6%
Third-party: 94%
WII
First-party: 74%
Third-party: 26%
PS3
First-party: 10%
Third-party: 90%
3DS
First-party: 43%
Third-party: 57%
PSV
First-party: 12%
Third-party: 88%
WIU
First-party: 82%
Third-party: 18%
PS4 (as 2020)
First-party: 16%
Third-party: 84%
NSW (as 2020)
First-party: 69%
Third-party: 31%
PS5 (as 2020)
First-party: 69%
Third-party: 31%
PS5 in 2020 was the first time since 2006 that a PlayStation console had more first-party sales than third-party sales at a certain point in time. It demonstrates the decline of Sony in Japanese territory. Sony was a third party driven
Source: InstalBase (thanks Celine)
