To the best of my knowledge, that isn't exactly possible. "Security Through Obscurity" ...isn't really an option within the ESRI framework wherein you share an item with Everyone in AGOL.
If you don't mind your Survey Form/Questions being visible, but want to limit valid submissions to your own organization, I have a suggestion: a secret password. It can't be "Swordfish," as that's the first thing I try when I see a password field. ...And to discourage the general public from trying "Swordfish" too, we'll need to hide the password field as well.
What happens here is a Publicly-accessible Survey123 form created in Survey123 Connect:
Valid Users access the Form via a URL (with an encoded URL parameter) that loads in a predetermined "secret password." Valid Users' submitted forms may be separated out from other form submissions.
Place the valid-access URL link inside your organization somewhere. I use an intranet-type page.
Basic Blueprint:
In Survey123 Connect, open up the XLSForm.
Create a Text Field, and name it whatever you want. Anything. L337c0d3, as an example.
Set the field appearance to hidden. Also make the field Read-Only AND Required.
In this example, I'm going to say that the correct password is Swordfish.
At the tail-end of the eventual hyperlink that allows access to your survey, just add &field:L337c0d3=Swordfish
Results:
Publishing the form for the world to see creates a few things. Within your own Survey-_____ AGOL Folder, there’ll be a Form and a Feature Layer (hosted) that show world/public sharing status; there may also be a Feature Layer (hosted, view) of submitted record locations just for AGOL. The Feature Layer (hosted) has a glowing blue crayon next to it, signifying that it is approved for “Public data collection.”
The Feature Layer (hosted) that is used to collect survey response locations can be used to create hosted Views. A View is a re-interpreted item, subject to the limitations specified when building the initial View; changes may be made afterwards, if needed.
Any Hosted Views may be updated from the Settings tab to include a filter that removes non-official values of L337c0d3.
I've used this basic structure for a couple of in-house critter surveys, and it seems to work pretty well so far. Submitted responses are not visible to the world, and if we wanted to get creative, we could assign unique passwords to individual groups of employees to further group the responses (since it is a public survey, we didn't ask for who submitted the record; assigning passwords by region would allow us to see how wide-ranging each division collected information). The creation of a final Hosted View to filter out all but Valid Users of the Survey is just the final QA/QC step. While it is possible for a determined member of the public to find and fill the hidden L337c0d3 field, that last filter will catch those.
Eventually, I suppose I'll get around to posting some sterilized documentation of all of this.
