v4l2lepton not detected in Chromium/Firefox despite streaming working in ffplay/VLC

[kook-tech]

Hi, I'm currently working on a project using Lepton 3.5 with a breakout board on Raspberry Pi 5.
Since the v4l2lepton repo only supports Lepton 2.0, I modified it to support Lepton 3.5 and stream via a v4l2loopback device.

I created the virtual camera with:

sudo modprobe v4l2loopback video_nr=0,1 card_label="Lepton","LeptonYUYV" exclusive_caps=1,1,1,1,1,1,1,1

Then I stream using:

ffmpeg -f v4l2 -i /dev/video0 -vf "scale=640:480,format=yuyv422" -f v4l2 /dev/video1

Both /dev/video0 and /dev/video1 work perfectly with ffplay and VLC.
However, Chromium and Firefox do not list the devices when calling:

navigator.mediaDevices.enumerateDevices();

Loopback devices are configured with exclusive_caps=1, and v4l2-ctl shows video_capture only (no video_output), so everything seems correct. Still, the browser does not recognize the virtual camera.

Do browsers successfully detect the virtual camera when using v4l2lepton with a Lepton 2.0 module?

Any idea what could be missing or how to get browsers to detect this virtual webcam?

Thanks in advance!