If you are using a desktop browser and you only want to search a particular location, there is a third party browser add-on called "eBay item location -- my country only" that can be used to override eBay's default item location setting.
If you use the eBay app, you can enable lockable filters in the Filter Customization menu, and then set your item location and tap the padlock icon to lock the setting for future searches.
Keep in mind that just because a seller lists an item as being shipped from the US does not always mean that the item will actually ship from the US as it should. Keep an eye out for signs that the seller is misrepresenting the item location by checking feedback and shipping estimates.
