Well actually I found a way.
Insert a sidebar widget in Elementor that references a sidebar from your theme then in that sidebar under appearance put the widget (ie image) that you want to be sticky.
Ps.. I am surprised at your outright dismissal, there is always a way (If you don’t find it someone else surely will.) and I am sure elementor would help you integrate your plugin with there’s. Elementor is already the most used pagebuilder and developers are jumping on board with amazing addons.
Let this be a challenge to you then to find a way, no disrespect meant.
https://github.com/pojome/elementor/tree/master/docs