According to Apple's own orders, shipments in the US have dropped by next Tuesday, while pick-up in the store is no longer available. Typically, Apple reserves some devices for "walk-in" customers, so you can still find them in the Apple Store on the release date.
And if that does not work, outside vendors like Best Buy seem to have supplies in both Space Gray and White.
Initial HomePod orders were available from Friday, January 26, so it took some time before stocks were exhausted. It is not clear how much Apple supply was produced on the release date.
Usually, when Apple enters a new product category, the company quickly sells units. But it is very possible that the high price and lack of HomePod function could trigger interest.
In every way HomePod provides an amazing sound, but its smart home capabilities leave much to be desired. Add to this that Google Home and Amazon Echo are everywhere, and Apple has a tough battle.
HomePod officially starts on February 9