Hi there,
as Leo said Elementor Canvas replaces the theme template and therefore strips out all the hooks. I did think that the WP_head hook still exists so that should work. But maybe noe.
But instead of using Canvas you can use the Default template. Then create a Layout Element:
https://docs.generatepress.com/article/layout-element-overview/
In the layout element you can remove all the theme elements and set it to a pagebuilder container (contained or full width). Then you have the same as Canvas but all the goodness of GeneratePress.