You can set a backdrop image for your strip:
the limitation is that you cannot upload just any image
it has to be a panel drawn by you or someone else on this site

For this tutorial we will use Electra 's Backgrounds strip

Under Strip Edit

Select Extra Tab

Page Backdrop Strip ID ←- this is the strip the backdrop is in

Image Index ←- order of the image in the strip (1 is the first)

Fixed Backdrop ←- set this to make the backdrop stretch onto the screen

You can get the Strip ID from either the header of the page:

or from the URL of your browser:

Image index is also simple:

Example settings:

Final result: