The Google Express app just got an update that adds support for shared shopping lists that others can be invited to edit, and also drops support for Android Jelly Bean, i.e. all versions between 4.1 and 4.3.1. Shared shopping lists, including those that you didn't originally create, can be edited and updated from your phone, desktop, and via Google Home, thanks to the Google Assistant. They can also be shared by anybody who's editing them, but only the original creator can invite a new editor into a shared list. As a bonus, the app got a few unspecified performance fixes and a new logo.
This update is directly related to the fact that the Google Assistant, and consequently Google Home, no longer save shopping lists to Google Keep. Google warned users of the upcoming change well in advance, and asking any Assistant-enabled device to add an item to your shopping list will now send it directly to Google Express, though some users are reporting they have other options in some cases, though Google Keep is not one of them. This change will presumably also apply to shared lists since shopping lists maintained and edited semi-automatically through Google's apps will no longer default to Google Keep. Looking at the reviews listed on the Google Play Store since the update suggests many users are not fans of the change and are asking Google to either shift things back to Keep or give them a way to choose between the two on their own. Only time will tell if Google listens to that feedback, though more information on the matter should be available shortly.
Since this app strictly requires an internet connection, it is to be assumed that running legacy versions on old versions of Android could cause problems, or may not work outright. Naturally, users outside of Google Express' service areas can still use the Google Assistant to save shopping lists to Express for use elsewhere. Previous updates to both the app and the service saw it striking partnerships with more stores and expanding to a larger number of states, especially those along the east coast.