[α/Fe]–[Fe/H] diagrams for DESI EDR and APOGEE reference sample. From left to right: (1) DESI SP: DESI SP pipeline, (2) MLP-Scratch: MLP trained from scratch on the same number of DESI spectra used for fine-tuning, (3) MLP-LRS: MLP pretrained on LAMOST LRS (zero-shot application), (4) MLP-LRS (fine-tuned): MLP pretrained on LAMOST LRS and fine-tuned with DESI spectra, and (5) APOGEE: DESI DR1–APOGEE DR17 crossmatched sample (7608 stars). The first row shows raw counts, and the second row shows column-normalized densities, where each [Fe/H] column is divided by its maximum count. The legend reports the maximum mean discrepancy (MMD) between each sample and the APOGEE reference.