Bend Studio acquired in 2000- notable IP at the time, syphon filter 1 & 2 ( As a different studio)
Bluepoint Games acquired in 2021- notable IP at time, remakes of Demon’s Souls, Shadow of the Colossus, and remasters of Gravity Rush and Uncharted 1-3
Firesprite acquired in 2021 - The Persistence
Guerrilla Games founded and acquired in 2000
Haven Studios founded 2021 acquired in 2022
Housemarque acquired in 2021 - Returnal, Resogun, Alienation, Super stardust
Insomniac Games acquired in 2019 - Ratchet & Clank, Spyro, Resistance
London Studio founded in 2002
Media Molecule founded in 2008 acquired in 2010 - little big planet
Naughty Dog founded in 1984 acquired in 2001 - crash bandicoot 1 & 2, and Crash racing
Pixelopus founded in 2014 (college grad students)
Polyphony Digital founded in 1998
San Diego Studio founded in 2001
Santa Monica Studio founded 1999
Suckerpunch founded in 1997 acquired in 2011 - Sly Cooper 1-3, Infamous 1 & 2
Team Asobi founded as a division of Japan Studio in 1993
Then there are the support studios….Valkyrie, Xdev, Nixxes, San Mateo, Studio Malaysia. You can see from this list that sony has never made any acquisitions as a company that have pulled any real amount of 3rd party support from other platforms. Almost all their current successful studios were either founded by them or acquired off potential to produce bigger more popular games.
The one exception being Bungie, who not only right off the bat committed themselves to future multiplatform development but have mostly been acquired to even further support the expansion of sonys own studios with their multiplayer efforts.
I can make the same list for Nintendo. I would love to see someone make a list for Microsoft.