I wish it were possible to press a keyboard shortcut while in full-screen Safari, have a finder window appear in the middle of the screen, and then drag+drop files from that finder window to safari.
How can I do this?
Ask Different is a question and answer site for power users of Apple hardware and software. It only takes a minute to sign up.Sign up to join this community
Rather clunky, but possible...
Go back to Finder, select & grab your files; keep hold of them.
This is always going to be hindered by fullscreen apps being to the right of any & all numbered Spaces.
You may need to enable the Ctrl/key functionality first in System Prefs/Keyboard/Shortcuts/Mission Control
Only alternative I can think of is use the Open dialog, or as suggested elsewhere, don't fullscreen, just maximise.
Unfortunately no applications can run on top of a full-screen application. Not even stickies, which work well on top of other applications. If you want a similar full screen effect while using finder on top you can use these 2 methods:
Click on Window on the top status bar than click on Zoom to widen the viewing angles.
Place your mouse arrow near the corners or edges of the Safari window and then stretch Safari all of the way to each section of the Mac display.
Either method will allow you to view the website and still keep the Safari screen large while multitasking via another application.