"We're trying to simulate in the laboratory this very early process when a planet's atmosphere is forming so we can put some experimental constraints on that story," Telus said. "It may seem arbitrary to use meteorites from our solar system to understand exoplanets around other stars, but studies of other stars are finding that this type of material is actually pretty common around other stars." The researchers found water vapor to be the main gas produced by the meteorites during the "baking" process, but the rocks also produced significant amounts of carbon monoxide and carbon dioxide and smaller amounts of hydrogen and hydrogen sulfide gases. "
Interesting approach here using meteorites from our solar system. Some exoplanets have atmospheres detected but this is very difficult. "We report the detection of an atmosphere on a rocky exoplanet, GJ 1132 b, which is similar to Earth in terms of size and density. The atmospheric transmission spectrum was detected using Hubble WFC3 measurements and shows spectral signatures of aerosol scattering, HCN, and CH4 in a low mean molecular weight atmosphere." Apparently this hot super-earth (temp near 529 K) has H2 as well detected. Ref - Detection of an Atmosphere on a Rocky Exoplanet, https://ui.adsabs.harvard.edu/abs/2021AJ....161..213S/abstract
Telescope Teamwork Reveals Gas Dwarf Planet's Atmosphere, https://www.space.com/nasa-telescopes-reveal-exoplanet-atmosphere.html
, July 2019. "...The scientists predicted GJ 3470 b's atmosphere would be full of oxygen and carbon, the same elements that are at the root of the water vapor and methane gas observed at Neptune. "Instead, we found an atmosphere that is so poor in heavy elements that its composition resembles the hydrogen- [and] helium-rich composition of the sun," Björn Benneke, lead author on the new research and an astronomer at the University of Montreal, said in a statement. What's more, the team thinks they may know why GJ 3470 b's composition is so different than that of Neptune's: It has to do with the planet's origin story..."
Detecting atmospheres on the 7 exoplanet system TRAPPIST-1 apparently remains to be confirmed. There are stars with 8 exoplanet solar systems like KOI-351. Kepler-80 has 6 exoplanet system. Do we have meteorites from these solar systems? Apparently not. There is more than 700 stars documented now with multiple exoplanets in orbit from 2 to 8.