with these tips, im assuming you are an going to buy things yourself on your own. those are tips for reallife shops, since im from poland i dont really know how shops look in the rest of the world, so i apologize if some stuff is impossible fo you...
i wanna buy baby stuff for myself (or my little)but im too emberrased
what is the giftcard trick you might ask? its simple. if you have some extra money to buy a cheap giftcard with words like "congratulations" or "welcome to this world!" people will assume, you are a caring friend getting baby stuff for your pregnant friend, idduno if cards or bags are cheaper, but you might also wanna get a gift bag instead, same result.
dont frantically reassure your cashier its for a friend unpromted, if you are stressed about it, they will assume you are lying, most of the time you dont have to reassure, from what i noticed, if you just casually walk up to cashier and hand in the items, they dont seem to question anything.