Wikipedia now lists dozens (hundreds?) of known argon compounds, so the concept is nothing new. Most are a bit contrived, but one compound that could have a real existence on Earth -- or rather, in Earth, is a nickel-argon compound:
At 140 GPa and 1500K nickel and argon form an alloy, NiAr. NiAr is stable at room temperature and a pressure as low as 99 GPa. It has a face-centred cubic (fcc) structure. The compound is metallic. Each nickel atom loses 0.2 electrons to an argon atom which is thereby an oxidant. This contrasts with Ni3Xe, in which nickel is the oxidant. The volume of the ArNi compound is 5% less than that of the separate elements at these pressures. If this compound exists in the core of the Earth it could explain why only half the argon-40 that should be produced during the radioactive decay that produces geothermal heating seems to exist on the Earth.
There is an implication in the above passage that argon can assume a partial negative charge, despite ostensibly having full valence subshells, a feature not evident in the more usual noble gas compound choices such as oxides and fluorides.
Dalton, Louisa (30 October 2019). "Argon reacts with nickel under pressure-cooker conditions". Chemical & Engineering News. Retrieved 6 November 2019. Electronic link goes to Ref. 2.
Adeleke, Adebayo A.; Kunz, Martin; Greenberg, Eran; Prakapenka, Vitali B.; Yao, Yansun; Stavrou, Elissaios (15 October 2019). "A High-Pressure Compound of Argon and Nickel: Noble Gas in the Earth's Core?". ACS Earth and Space Chemistry. 3 (11): 2517–2524. Link