Even the high-res version (20 MB) of the Bremen image seems to be about 17-25m per pixel based on the 50m wide airport runway being about 2-3 pixels wide in the image.
Copernicus browser claims 10x10 meter pixels (which seems to be correct) but the actual resolution of the radar is supposed to be 5m-x-20m for the standard IW mode. I assume "high resolution" here means the data should have 5m x 5m resolution (Strip Map mode) which in Copernicus browser claims 3.5x3.5m pixels.
The images on the page are not the high resolution images, they are resized as the full res versions are over 20MB. If you take the image, you'll be taken to a download page where you can get the full res version.
These replies prompted me to go looking. Firefox Android (which I'm using) does have an option in the settings under Accessibility called "Zoom on all websites". It works!
Chrome has a similar option, which also works on this site. I expect this might break a few pages, but Google Maps and OpenStreetMap work fine, with pinch zoom zooming the map when you do it on the map.