Unfortunately unless you get into more advanced JavaScript I don’t really see that happening.. I’m not too familiar with the Discourse JS API but it seems to be as easy as taking the URL, putting wrapping it in <iframe src="..."></> and replacing /edit with /pubhtml?widget=true&headers=false
I would recommend making a tutorial post of sorts informing your community members on how to properly export it if this is a big concern, that or you can always request official onebox support in Contribute > Feature