oh i hope it's not too late, in terms of stock cars that are ready for sand offroading from the get-go, I'd vote for @RiadJL & @Gautam Banka 's Jeep 392 V8 HEMI 6.4L that already comes with winch and proper wheels ๐ Albeit, I'd still modify 392's cooling, since it comes with electric fan from stock (friend says the 392 overheats in advanced drives).
Similarly capable from showroom would be @Dodi Syahdar Bronco Raptor edition ๐.
But the car I'm still amazed with, even with limited parts availability, is @Srikumar & @Brett Eicher's Jeep Cherokee ๐ฅ That classic can still climb dunes very well ๐