The sonata_page_render_container
function takes the following arguments:
public function renderContainer($name, $page = null, array $options = array())
So you have the third argument to specify some options/settings to add to your block, like this:
{{ sonata_page_render_container('footer', 'global', {mysetting: myvalue}) }}
After that, you can modify your execute() BlockService's method to use the settings you passed.