You're going to have to provide a link to whatever you're talking about. The Pi Pico is the only hardware product that the Raspberry Pi Foundation is releasing to the general public today. They have partners releasing other products based on the RP2040.

I think you're referring to the Pi Pico, but you think it's called something else. There is no product called "Pi Si", as far as I can find. The link that this HN post is pointing to is about the Pi Pico.

If you're just referring to the chip itself ("Raspberry Silicon", "RP2040"), all surface mount chips have to be used on a "motherboard" (PCB) of some kind, so the question seems irrelevant. Based on the datasheet, yes, the chip seems to have no internal flash, so you have to use an external flash chip, but even if it did have internal flash... you would still have to use the chip on a PCB, so it doesn't matter in regards to the original question.