I noticed that GOG now offers a public facting game collection page for your profile so perhaps you could add importing this to the import options instead of the copy-page option. My link to my collection is https://www.gog.com/u/Marcelloz071/games (you only have to set the privacy settings correctly)

I also think the current option doesn't work anymore as I could not select the page content using ctrl-A. It highlighted the menu but nothing more.

Oh nice, I didn't realize they changed this up again. I think the challenge here would be that the page utilizes "infinite scrolling" and loads content dynamically, so I would somehow have to load the page in a browser (via code) and scroll to the bottom until it stops loading.

I noticed that as well, though copying the games list from the profile page is a possibility for the user after they've scrolled to the bottom (followed by a quick chomp to remove playing time/achievement progress/extraneous data)