And yet Husky and Avalanche succeeded, the latter with German Panzer divisions located at the beaches.
They did. Massive differences however.
The Husky amphibious landing force was less than half the size and strength of the force that landed in Normandy (~2,700 vessels vs 6,900). Opposition was primarily two strong German divisions and the Italian 6th Army, which was of very uneven quality, although some elements fought very tenaciously, many others folded. This can be best illustrated by the fact that the U.S. landing force suffered 58 KIA, 199 WIA, and counted 700 MIA at the end of the first day, having created a solid lodgement and taking 4,000 prisoners (TOTAL Heer casualties on D-Day were roughly 1,000), with The Canadian 1st ID taking an additional 500. However the Italian "Napoli" offered fierce resistance.. The Axis forces on Sicily had very little hope of worthwhile reinforcement, again a huge difference that that which existed in France.
Avalanche's landings near Salerno did indeed occur where the 16th Panzer was charged with the defense. 16th Panzer also had to defend the entire Sorrento Peninsula and the shoreline south to Agropoli, and do it alone, since the Italian force originally assigned to provide defense of the region had been withdrawn with Italy's surrender. This left the Division to cover well over 50 miles of frontage with virtually no shore defenses beyond some barbed wire and a belt of Teller mines. This being the case the Divisions CO had spread his armor out in "penny packets" in hopes of disrupting any landings. This vastly diluted the potential combat power of the Division, as can be seen in the combat histories of the 36th Division were number attacks by anywhere between four and fourteen Pz IV are noted, none of these small platoon/company size attacks managed to penetrate defenses thrown up by the assaulting battalions. It is an interesting WI to consider what might have happened had the 16th Panzer managed to maintain it armored forces in battalion size groups rather than the much smaller unit attacks.
It is also critical to note that at both Silicy and Southern Italy the commanders of the landing forces made errors that, had they happened against the far more substantial Heer forces available in France instead of Italian conscripts with sub-standard weapons, training and very uneven leadership or widely spread out Herr forces would have been disastrous.
Enemy air opposition to the two landing was also manageable, although the WAllies did not enjoy the virtually uncontested airspace the existed over Normandy in mid 1944. In 1943 the WAllied air forces would have been hard pressed to manage air parity and any paratroop or glider deployments would have face not just AAA but Luftwaffe Nightfighters. Even if the RAF/8th AF managed to keep Luftwaffe attackers away from the landing forces the effort would mean that the huge amount of CAS that the landing forces enjoyed, and the ongoing interdiction by fighter bombers range over the landing area would have been diverted to the air battle. In Spring-Summer of 1943 the 8th AF was still getting slaughtered over Germany and the lack of fighter escort deep into Germany was preventing the hammer & anvil tactics that, combined with the CBO, over the following year destroyed the Luftwaffe as a fighting force.
Lastly, a specific word about the chances for a 1943 landing. As late as mid 1943 the U.S. & British were still working out the whole "landing craft" idea. in March of 1943 (and this will sound distressingly familiar) the British were actively working on the conversion of barges and coastal steamers for at least the follow up waves of any landing force. The landing craft that were available in their literal thousands, and not even begun to be constructed in sufficient numbers (the first LCT was not even delivered until September of 1942). One thing that is often overlooked when discussing things like landing craft is that the WAllies didn't land that many more troops in the first wave on D-Day than was the case in the Med, but those troops were just the door kickers, in the three weeks after the initial landings the WAllies inserted an additional 710,000 troops, with many more following in the following months. The WAllied didn't HAVE 875,000 troops in the entire ETO in mid 1943. Many of those men were either just finishing recruit training or had not yet even received their orders to report for induction. Even with the extra year to build up forces it was necessary to pull divisions out of Italy to reinforce the French campaign (it wasn't just Mark Clark's command skills that effectively ended the offensive up the Italian Peninsula/
tl;dr: Not the same situation, at all.