Aurélie,
If you prefer to go for the 2nd option from my suggestions above, which is customizing the source code of Survey123 field app. This is the simplest code change I could think of, this is done on template/SurveyGalleryPage.qml
Component.onCompleted: { app.openParameters = JSON.parse('{"itemID":"814e2804146341c89c237d166de19b0b"}');
}
So I instead of opening the Survey123 using custom URL scheme explained above (1st option from my suggestions), we are going to add a block of code setting that `openParameters` as if we have a parameter, which is the itemID of the survey that you want to open.
I have tested this, now the Survey123 field app will open a predetermined survey that you set in that block of code. But please take this solution with a grain of salt, as this is just a quick hack to prove that it is easy to do.
Also please note that this will open a survey that is public as you are required to login for surveys that are private or shared with an organization.
I hope this helps,
Erwin.