First-principles insights into the mechanical, optoelectronic, thermophysical, and lattice dynamical properties of binary topological semimetal BaGa2

•BaGa2 is soft, highly machinable, borderline brittle, elastically and dynamically stable.•BaGa2 is semimetallic with quasi-2D Dirac cone at the Fermi level.•Admixture of ionic and covalent bondings dominates in BaGa2 with some metallic contribution.•Absorption, reflectivity and refractive index spectra of BaGa2 show features suitable for applications.•Calculated thermophysical parameters are consistent with each other.