https://askubuntu.com/questions/1051207/snap-how-to-grant-permament-permission-to-read-folder
@oSoMoN do you know the answer to this question? 
The pop-up is triggered by the in-snap xdg-open command AFAICS, implement an “Always allow” checkbox might be feasible.
Is there any news about this checkbox in order to always allow an app to use xdg-open ?