I am trying to access a public form and its associated public hosted feature layer in the Survey123 App without an AGOL sign in.
I'm calling the form using the custom URL:
arcgis-survey123://?itemID=b65be973015243768ab0c0216a96bd39&field:ArboristCooperator=Dudley R. Hartel&field:ITFD_ProcessStatus=NewDataPublicAccessHFL
to pass values to 2 attributes ArboristCooperator and ITFD_ProcessStatus. This part works.

Without my desktop App signed in, it opens, the form loads, I can enter the data; but, even when the form and HFL are both shared as "public" I get this error.
Is this (accessing a form thru App without sign in) just NOT supported?
Our objective is to provide easy access to non AGOL users (i.e. public form) with limited (or controlled) distribution of the App custom URL to qualified participants and have a value (in this case ITFD_ProcessStatus) set a "security key" that can be used in AGOL post-processing for QC.
Someone that might "find" the form and open it in a browser would be entering data without the passed values for our security RC post-processing (and we could deal with it).