While waiting for this feature, you could use a hidden popup to store all your variables instead of custom states (credit to AirDev and @vlad for this pro tip).
So instead of creating a custom state, you create a popup and add groups or repeating groups, for single values and lists respectively.
These are actually more useful than custom states because they can have default data sources, conditional data sources, or have their data set by a workflow.
Since I learnt this approach I never use custom states in my app again.
Thanks again @vlad or whoever in AirDev that came up with this strategy. It’s the beat pro tip I’ve ever had in Bubble.