I can't pick up in any Store for iPhone 15? Help

No one here could possibly know or help you. This is a user to user only forum. If the option to pick up isn't available, its because the store you want to buy from doesn't have them in stock to be picked up. When the store you want to pick up from has them, we wouldn't know. You'll have to keep checking OR just place your order and Apple will ship it to you (in the country of purchase).

We, just users like you, are not aware of Apple products availability/stock, sorry.

As suggested at the bottom of your screenshot, "Chat now or call 1-800-MY-APPLE" and ask there.

Regards

Giulio