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Would fluorocarbons be detectable in a remote spectrogram of the atmosphere at the levels they existed in the earth's atmosphere? Would the depletion of ozone in the atmosphere be more visible?

From [0] it looks like CFC's peaked on the order of 1 ppb. Humans (perhaps) just detected phosphine at the level of ~20ppb in Venus's atmosphere through telescope spectral analysis [1], but that's on a very close planet that we've been staring at intently for 4000 years; presumably there are compounds present in smaller concentrations that we haven't seen yet. Is there a heuristic for the hypothetical minimum sensitivity relative to interstellar distances?

[0] https://www.esrl.noaa.gov/gmd/hats/about/cfc.html [1] https://www.nature.com/articles/s41550-020-1174-4