According to Gemini:
No, the Springfield Armory XDM (and XDM Elite) was never factory-produced in .357 SIG.
While the original, first-generation XD line (specifically the 4-inch Service and 5-inch Tactical models) did come chambered in .357 SIG, Springfield Armory skipped the caliber entirely when they upgraded to the XDM series. The XDM line was strictly limited to 9mm, .40 S&W, .45 ACP, and later, 10mm Auto.
If you have seen an XDM firing .357 SIG, it was modified. Because the .357 SIG cartridge is based on a necked-down .40 S&W case, shooters frequently buy an XDM chambered in .40 S&W and drop in an aftermarket .357 SIG conversion barrel (made by companies like EFK Fire Dragon or Bar-Sto). Since the rims are identical, the factory .40 S&W slide, extractor, and magazines work seamlessly with the conversion barrel.
FWIW