Big Walk is not listed for PS4
The official Big Walk FAQ lists PlayStation 5, not PlayStation 4, among the supported platforms. It also states that no other platforms are planned at this time.
That means players should not expect a PS4 version based on the currently published official information. This page will be updated only if House House, Panic or PlayStation announces a change.
Where PlayStation players can play
For PlayStation, use the official PS5 product page. It is the reliable place to confirm store availability, region-specific price, online requirements and account notices before purchase.
Crossplay is supported between the game's supported systems, according to the official FAQ. Platform support is still separate from crossplay: a PS4 console is not included in the listed platforms.
Do not rely on compatibility rumours
Store tagging, backwards-compatibility speculation and social posts are not a PS4 release announcement. Treat only a product page or an announcement from House House, Panic or PlayStation as confirmation.