Okay I had an initial look at it. I'd somewhat describe that link as being "misleading".
There isn't actually a PDO driver. You'd have to use their turso/libsql package which is a native PHP extension using FFI/Rust which means it likely needs additional compilation/configuration in PHP. It also requires the use of their Database class which means it would require a separate XenForo adapter which we're not planning at this time.