10+ years ago I wrote a GreaseMonkey userscript for a dating site that collected all your results into one scrollable table. It exercised very explicit control over the image loading sequence. If I recall (and my memory might be spotty), it grabbed 1 thumbnail image per match initially, in the order they were displayed, to populate the table. Once all the thumbnails were pulled (which didn't take very long), it would start downloading full sized images, in the background. Hovering a match to view more details would immediately prioritize that matches photos, and if you hovered over one of said match's photo thumbnails (as if to click) that specific image would be placed at the top of the queue.
It was all done using Javascript (no frameworks) and XmlHttpRequest, and worked pretty well. This was back when servers only allowed you a couple (or handful) of connections at a time. I wrote a "TaskQueue" class in Javascript implementing a very simple form of cooperative multitasking (jobs designed to do their work in chunks). Tasks could "preempt" others, and you could define simple relationships so a group of tasks could block on one they were dependent on.
Funny story, I actually sent a link to the tool to a girl on the site who I eventually wound up in a long-term relationship with ("here, let me help you make it more efficient to browse for other guys...").
Anyway, at the time I felt like it was table stakes that a page like this should be able to exert some sensible control over the sequencing and prioritization of its image assets, in a fashion that has the user's best interests at heart. I'm glad browsers have finally evolved out-of-the-box attributes like "loading=lazy", but I kind of wish there were an option between "eager" and "lazy" that simply deferred the lazy content until all the other content is done. So I can still walk away to get a coffee (or switch to another tab) and come back to a fully, instantly-responsive page.
