YSK: You can block almost all cookie popups with Ublock Origin.
On ublock origin (full version, not lite), click on the settings icon:
Then go to "Filter Lists" and enable both of the "Cookie Notices" options:
I occasionally do searches to see if there's a blocker for those obnoxious, "Do you want to use the app?" lightboxes. To no avail. đż
Ublock Origin also has a section called annoyances, some of those lists probably block them.
AdGuard has a filter list for Mobile App Banners.
You can make your own filters. Press the zap button to temporarily block something (to test) and the eyedropper to permenantly make a filter.
I try that in uBlock from time to time, but I still can't seem to get it quite right. Testing in Duolingo right now, I set it to get rid of the app popup, as well as the semitransparent overlay that darkens the whole page. But there's still some element on the page that restricts me from scrolling until I tap on the page. It's an improvement, but still not quite there yet.
I just imported it, and still have to tap before I can swipe. I also checked eBay after importing, and that app banner still pops up.
Is "lightbox" another word for "modal"?
I had to look up 'html modal', yeah it sounds like the same thing. I learned web dev back in the xhtml days. Back then those kinds of boxes were only beginning to see popular usage, and there was no official tag for making them.