Abstract: Io's volcanism was first seen indirectly: as a sodium cloud and a repeating plasma radio burst signature. The same signatures are studied at exoplanets. At spectral resolving powers near 100,000, alkali doublets separate gas bound to a planet from satellite material in orbit due to unprecedented Doppler shift resolution techniques. At the hot Saturn WASP-49 A b, several transits from HARPS to the Keck Planet Finder show sodium that varies nightly as expected for a satellite orbit, detected in redshift at +9.7 ± 1.6 km/s. I present a population study of sodium at hot Saturns and a transit of HD 189733 b from Keck Planet Finder and JWST transits of WASP-39b indicative of volcanic, close-in exomoons . As multiwavelength searches for exo-Ios are especially pivotal for orbit reconstruction, I also provide evidence of an extrasolar plasma torus in radio emission from an ultra-cool dwarf. Lastly, JWST lava planets and habitable exomoon predictions are discussed for the ELT and the Habitable Worlds Observatory.