Note that the home interface will grant access to most .hidden files apart from ~/.hidden (i.e. the one directly in the user’s home directory).
If the aim is to present a file chooser consistent with unconfined apps on the host system, it’s probably better to rely on xdg-desktop-portal though: access to ~/.hidden is just one of the many differences.
while you may be able to see the hidden files with the file picker you will get permission denied if you try to open one. I’m running into this issue with my app.