And with Attica taken the only road out of the Peloponnese is taking a boat from Rio and Patras to the opposite coast, straight into waiting partisans and bad roads.
In OTL that was the OOB of the Axis in the Peloponnese:
2 Italian infrantry divisions of the 11th army. However, there was a 3rd division (Sienna) that was transferred in summer 1943 to Crete. So I guess that in TTL there are 3 Italian infantry divisions.
4 German divisions, 3 infantry and 1 panzer. It should be mentioned that in OTL there were the equivalent of 3 more German divisions in Crete and Rhodos. Now, with the Peloponnese
much more exposed than in OTL, I guess at least
some part of those troops are redirected in the Peloponnese.
Overall, I think that there would be at least 7 Axis divisions in the Peloponnese (possibly up to 10), one of them panzer. This order of battle is excluding the garrison of Athens that was in OTL an Italian field division in addition to various other units. A large part of said garrison had to cover the entrance to the Saronic Gulf and the naval forts in the area.
As Lascaris said, the Axis in the Peloponnese have to cross the sea to other side via Patras. That being said, the ports on the north side were basically fishing villages with little infrastructure and Patras harbor never had a great deal of big ships during the Axis occupation. The evacuation would need to be done mostly via boats under constant air threat (Cretan airfields are close by). That doesn't bode well for evacuating heavy equipment.
Lets say the Axis manage to evacuate most of their troops minus equipment. Immediately after landing there are faced with 2 options: try to reach via the mountains Lamia, a train station at the other side of the mountains. Basically they would have to cross 170km of this terrain
https://www.travelstyle.gr/wp-content/uploads/2017/12/oreini-naupaktia.jpg , on foot, in a partizan-infested region. The Allies on the other side, to reach Lamia they have to cross 210km of mostly flat terrain that has the best road network in Greece at the time. Moreover, there is
not a single large enemy formation between Lamia and Athens according to the OOB.
The most reasonable choice for the Axis is to retreat towards Epirus, via the same difficult terrain but at least with no danger of being totally cut-off in >1500m mountains. That is a long trek. The next railhead to that direction is 300km away and they would have to cross even more mountains.
Wth the landing in the east of Attica basically a whole Axis field army is cut off and has no good choices. In the best case senario a large part of this force is bagged. In the worst case senario, this force looses its heavy equipment, suffers serious attrition and is out of action for weeks at least.
Edit:
@Aristomenes In OTL the only panzer division was in Peloponnese. The Germans had only 1 mountain division near Thessaloniki that could be transfered by train. Too bad that in OTL the partizans blew up strategic bridges to the south. So, the only reserves available in the Axis OOB are 2 Italian Infantry divisions in Thessaly.