Sony's PlayStation Studios stable of developers are currently making more than two dozen new games for PlayStation 5 consoles, the company confirms.

Sony is accelerating PS5 games development to ensure there's enough pipeline content available when console stock stabilizes. In a recent interview with Wired, PlayStation Studios boss Herman Hulst says there are over 25 games in development for the PS5 and nearly half of them are new IPs. "There's an incredible amount of variety originating from different regions. Big, small, different genres." This is a pretty substantial comment that needs context.
How many of these are first-party games? PlayStation Studios consists of 12 worldwide-based teams ranging from Sucker Punch (Ghost of Tsushima) and Naughty Dog (Last of Us) to Sony Bend (Days Gone) and Sony Japan Studio (Demon's Souls). It's highly unlikely that each team is working on two games at once. For instance, Naughty Dog's Evan Wells says the studio isn't yet ready for multi-project game dev just yet.

What's more likely is that the lineup includes third-party projects from partners like the newly-formed Haven Studios, which partnered with Sony and is directly named in the interview (Jade Raymond leads Haven and the studio has been a haven for Stadia devs who left the ailing service).
It's also worth noting that some of these games are new IPs, which means early incubation phases and concepts.
Sony Bend, for example, is said to be working on a new original IP instead of Days Gone 2. New IPs can also lead to cancellations and significantly long development times, so don't expect to see many of these titles for a while.
Last but not least we have to consider the scope of the games themselves. Sony is indeed investing another $148 million into its first-party teams in FY2021 and the assumption is this extra cash will help boost big-budget blockbusters from the likes of Naughty Dog.
Hulst mentions the projects are "big and small," which is also interesting given recent reports that Sony is doubling-down on marquee titles. This comment indicates developers have express freedom to choose what projects they make...and could hint at a bigger service-based transformation for Sony.
Microsoft also empowers its developers with freedom. Xbox Studios teams are free to tackle passion projects like Ninja Theory's ill-fated Bleeding Edge or Obsidian's unique Grounded game. Game Pass affords this freedom and many devs have commented they can now make experimental games because of the service.
Sony too could be readying its own Game Pass competitor of some sort that affords this kind of freedom...but only time will tell on this front.