Only in that you have to provide a shipping address.

Q: Does it have to be my address?
A: No. You can have it shipped to whomever you want as long as it's in one of the regions where it is currently being shipped.

Q: Does it have to be my billing address?
A: No. You are asked for a billing address during the payment method steps if you don't already have one saved with a stored payment method.

Q: Can I use Steam Wallet funds?
A: Yes. You can even split the purchase between Wallet funds and another payment method (IE: Paypal, VISA, Mastercard, etc.)

Fair enough. This is what it looks like when I attempt to buy one.

Go to the Steam Deck product page:
https://steamproxy.com/steamstore/steamdeck

Click on the Buy now! button under the configuration that you want.

Go to your cart, if not taken directly there, to see the Deck you've chosen. You can add more than one if you like. Click on Continue to payment.

Fill in Shipping Information. If you have a stored payment method with the billing address stored, it should automatically fill these in. If not, enter the address that you want the Deck(s) to be shipped. It does not have to be yours but still within the Deck's current service area. The click Continue.

From here on the process is the same as any game purchase on Steam.

Enter Payment Method. This will depend on what you have or have not saved, or funded.

If you have enough in your Steam Wallet to cover the entire purchase price, you will go directly to the next step to Review and Purchase. If you want to choose a different payment method other than your Steam Wallet, click on the Change link next to that payment method and it will bring you to this screen.

If you don't have any Steam Wallet funds, it will ask you to choose a payment method. If you have one stored on the account, it will default to that one. If you don't have a stored payment method, or would rather use a different one, do that now from the list of supported payment methods.

If you have some Steam Wallet funds, but not enough to cover the entire balance, it will ask you to choose a payment method to cover the remaining balance. This is what you see in my screenshot. Again, it will default to a stored method if you have one. Choose the one you want to use.

The billing address is the one associated with the payment method which may differ from your chosen shipping address.

Then click Continue.

Review and Purchase. Now you're at the final screen of the checkout process.

You can see the Shipping Address you selected earlier with the option to Change it. The Payment method shows how you've chosen to fund the purchase. Here you can see for me that it's been broken down between my VISA and my Steam Wallet, also with the option to change these. For instance, If I didn't want to use any Steam Wallet funds, I would click the Change next to it which would take me back to the prior step to choose payment methods for each

Other than the number of Steam Points you earn and which Steam account this purchase will be associated with, click the box to agree to the SSA, warranty, and refund policy, then click Purchase.

Barring any payment issues or checkout errors, you should get a confirmation of purchase with an accompanying notification to the email address you have saved to the account.