In Star Wars: Episode IV: A New Hope, medals are awarded to the people who destroyed the original Death Star. In Star Wars: Episode VI: Return of the Jedi, another Death Star is destroyed.
Were medals awarded again, off-screen?
SOME medals were definitely awarded.
Star Wars Insider #160 had a story in its "Exclusive fiction" section called "Blade Squadron: Zero Hour".
In it, it mentioned that all B-Wing pilots got Medal of Bravery.
The ceremony on the flight deck was short and to the point... before proceeding to award the B-Wing pilots who had survived the battle of Endor their Medals of Bravery.
Aftermath mentions medals to Y-Wing pilots too:
Since she joined the fight, she has had two moments when she wept. The first was only months earlier, after the battle over Endor had concluded; after she and her Y-wing (and her laser-crisped astromech) emerged from the labyrinth of half-constructed passages inside the second Death Star—just escaping in a plume of flame as the whole thing began to implode and then explode behind her, the shock waves causing her little fighter to tumble end-over-end until she almost passed out. That night, she sat alone in a changing room on the star cruiser Home One, and sitting there half in and half out of her jumpsuit, she wept. Like a baby without its mother. Hard, racking sobs hit her like crashing waves until she was curled up on the floor, feeling gutted. A day later, she got her medal. She smiled, turned toward the applause of the crowd. She didn’t show them how stripped-down and scraped-clean she really felt.
I saw mentions of posthumous medal to Arvel Crynyd (A-Wing pilot who flew into SSD's bridge). But couldn't find canon source for that.
Basically, what this tells me is that everyone pretty much got a medal, we simply don't have one single Yavin-like ceremony, because:
The Rebellion got too big, physically/logistically, to fit into a large hall
They were too busy rushing to organize the next steps of the war - both "Aftermath" and Insider's story allude to that pretty strongly. Unlike EU with its Yawn at Bakura, New Disney canon basically doesn't STOP the war at Endor, it STARTS it for realz.