Representative DESI spectra and composition-dependent photospheric SED fits for DA and DBA WD sources. The expected Balmer and He I line positions are marked in the spectra where relevant. The DA SED was fitted through VOSA using a Koester DA atmosphere model, whereas the DBA SED was fitted using optical-only model selection from the Warwick/Tremblay 1D helium-rich LTE synthetic spectral grid. The WISE measurements were excluded from the DB/DBA model fit and are shown as independent tests of infrared excess.