It came out much later here than it did in the US, and you still can’t buy it directly from Valve - you have to go through an authorized third party. But I have seen the Asus ROG Ally in electronic stores. I’ve only seen the Steam Deck at one place, and I think that store has an arrangement to sell it exclusively. I haven’t been out looking in a few months, though.
As someone who switched from a console to pc gaming this generation, and started out with a cheap ass pc with meh specs, it will be more than good enough for most people just starting out in PC gaming.