Do you also need to import export values for each item in the list?
If you don't need export values and only need to add items to the list, there are a couple of free scripts out there, one by Keith Gilbert and one by Chuck Weger called ComboMambo (https://creativepro.com/a-script-for-populating-form-fields-in-indesign/) which should do the trick.
My own (not free) FormMaker add-on (https://www.id-extras.com/products/formmaker/) allows you to do this but also allows you to bulk import an export value alongside each list item. Very useful if you'll be needing to actually do something with th user-selection in your interactive form afterwards.
And on a UX/UI note, I wonder if a list with 900 entries really works for the end-user? Perhaps it would be better to split the list into several sub-categories to make it easier for the user to find what they need? Of course, I know nothing about your form, so perhaps this isn't possible or necessary here. Just a suggestion!
id-extras.com | InDesign tools & scripts for typesetters, form designers, and translators
AdChoices