PS5 Backwards Compatibility: Can You Play PS3, PS2, and PS1 Games on PlayStation 5? - Push Square
PS5 backwards compatibility will cover all PS2, PS3, and PS4 games according to Turkish retailer - NotebookCheck.net News
Recently there's an influx of “PS5 backwards compatible” articles on google reporting it will play ps1 through ps4 titles. If it's true, much respect to Sony. : r/PS3