If it's really a box = might be пачка then, something like this https://yandex.ru/images/search?sour...ted-query-serpfrozen fruit packet
пакет/ёмкость замороженных фруктов - these are sold in thin plastic 'boxes' inside a plasic bag... пакет or ёмкость?
the whole container with its contents = also упаковка Одна упаковка - Перевод на английский - примеры русский | Reverso Context
i.e. упаковка can be both a process and at times a container
https://yandex.ru/images/search?text...=213&noreask=1
https://yandex.ru/images/search?text...BE%D0%BA%D0%B0
Moreover, a container that is contained within an another container, can be called порция because this small container is of specific size for reason (63 грамма овсянки, remember?)
One can say also 'I open the bottle', right? In Russian, it would sound more natural, then "я открываю бутылку".I open the lid of the bottle