We are other end users, not Apple and can only refer you to what Apple have published, such as this article:
Shipping & Pickup - Shopping Help - Apple
looking at the section "Apple Pickup."It appears that times can vary by store locations.
Also note that if you buy a Mac computer with AppleCare+ in the US, you must return the device tothe US for AppleCare warranty service. Section 4.1 here:
https://www.apple.com/legal/sales-support/applecare/applecareplus/2205/220606_applecareplusmac_us.pdf
for iPhones and iPads it is even more restrictive:
Legal - iOS Warranty Document Us - Apple
which contains this:
IMPORTANT RESTRICTION FOR iPHONE, iPAD, APPLE TV and HOMEPOD SERVICE.
Apple may restrict warranty service for iPhone, iPad, Apple TV and HomePod to the country where Apple or its Authorized Distributors originally sold the device.
Much of this is not due to Apple being a stinker but to US Export of Technology restrictions.
So thoroughly think through your plan before you execute it.