xdg-desktop-portal-hyprland: Screensharing fails on NixOS

When launching the screen sharing on my NixOS setups, I encounter what seems a permission issue (here with OBS)

info: PipeWire initialized
info: Switched to scene 'Full desktop'
info: ------------------------------------------------
info: Loaded scenes:
info: - scene 'Alone':
info:     - source: 'Image' (image_source)
info:     - source: 'Video Capture Device (V4L2)' (v4l2_input)
info: - scene 'Full desktop':
info:     - source: 'Screen Capture (PipeWire)' (pipewire-desktop-capture-source)
info:     - source: 'Video Capture Device (V4L2)' (v4l2_input)
info: ------------------------------------------------
info: [pipewire] Screencast session created
Attempted path: share/obs/obs-studio/images/overflow.png
Attempted path: /nix/store/v5dd3g0kgk8pzjdkypky19qynwil100z-obs-studio-28.1.2/share/obs/obs-studio/images/overflow.png
info: adding 21 milliseconds of audio buffering, total audio buffering is now 21 milliseconds (source: Desktop Audio)

info: [pipewire] Asking for desktop
warning: [pipewire] Failed to start screencast, denied or cancelled by user

I installed hyprland using flakes and NixOS, I check the module and it seems this portal is added automatically to extra portals so my guess is the setup is pretty standard and foolproof and should work out of the box, but it is not the case.

I use nixpkgs on nixpkgs.url = github:NixOS/nixpkgs; (unstable).

Did I miss something or is there a bug ? I can provide more logs if you need, let me know.