check this thread on another open-source-into-company - timefold - (from last week):

https://news.ycombinator.com/item?id=42999454

and, suggestion for the no-api-required part: maybe something like hasura.io , that makes an api out of data-model/form. Though such survey-like data may go into kind of data-lake..? may be look at interfacing those as well..