Welcome to the forum.
FYI, for Japan there are a lot of middleman services available to purchase on websites that are just for Japanese residents. Buyee, FromJapan, ZenMarket, Noppin, etc. are all Japanese middleman service that lets you purchase or bid in auctions on among others YahooJapan and Mercari, and with most (maybe all) of them, you can also post URLs for their employees to buy on your behalf. (I recently bought some stuff directly from the Pokémon Center webshop through both Buyee and FromJapan for example.)
They will then be shipped to their warehouse, and you’d usually have 30 days to combine shipping towards your own home/PO.
Here a list from 2018 with some Japanese middleman services: Japanese Marketplace List
And here also a poll from 2025 with a more recent list: What's the Best Japan Proxy Buying Service?
Greetz,
Quuador