Superset

A single production instance of the SELV-Dashboard may eventually suffice. We don't necessarily see need for test of QA instances of it because:

A) The system’s automated and manual workflows are simple and limited. We thus reasonably expect changes to be made directly in production without first being vetted elsewhere.

B) Users will be extremely limited in terms of what system state they can change. It’s thus unnecessary to have a separate training instance.

C) We have access to, and can develop with, the systems’ actual historic data. There’s thus no need for an alternate system which uses test data.

Even after deployment, it will be viable to use the Production server for development. Things that are in-progress can be hidden from end users by excluding them on the main dashboard. A couple things to note (because "things" is a broad term):

1) Metrics can be flagged as private, so in-progress metrics can be completely hidden from end users https://superset.incubator.apache.org/security.html#restricting-the-access-to-some-metrics

The only other restriction that Superset (currently) allows is at the data source level. I would not recommend having a separate data source for in-progress slices and dashboards, although that could be an option if the two points below are concerns for you

2) Slices / charts are found in their own menu, and that is not accessible for the Gamma user role (which most users will likely have). So, in-progress slices can be hidden

3) Dashboards (the menu for which Gamma users will have access to) will be viewable. So, you can prefix their names with IN_PROGRESS or some such thing. There's also an "Owners" field in the dashboard editor that is the list of users who can ALTER the dashboard. Those users can still view the dashboard. So, if there's concern about users viewing but not editing a dashboard labelled as IN_PROGRESS, this could be a problem. I should note that building a dashboard is relatively straightforward, presuming you've assembled the slices / charts and metrics already. It takes like 5 minutes to arrange the slices and whatnot on a dashboard. So, I don't imagine you really needing to have a dashboard that's in progress - most of that work is done in slices and metrics