I've been storing time-series data using MongoDB connector.
It's ok to "find" data with the MongoDB Binding and display it in a Time Series Chart.
In my opinion, is clear that the Power Chart component is not capable to display this data yet.
Would it be capable to do so in a near future?
How the document fields should be to obtain the "same" behavior with SQL data?
The Power Chart obtains it's data through Ignition's Tag Historian querying API. So in order for the Power Chart to use data originating in MongoDB, we'd first have to implement a Tag Historian implementation that used a MongoDB backend. We currently don't have any active plans to do this.
It is certainly "okay" to do this yourself by binding the data of a Time Series Chart to a MongoDB query.