The closest I've heard of is some seabed oilfield sequestering from Nordic countries, IIRC, but that has some built in limitations.
Are you aware of sequestering efforts I've missed?
Though I have no idea if we can make enough salt caverns, at least it would be a fixed amount of salt caverns, since you could establish a closed-loop supply of liquid fuel this way that was long-run carbon-neutral.
It's just that some emission reductions are also open technological questions, and sometimes they're more or less open than the questions around sequestration, so hard-and-fast rules are hard to come by. Is it easier to sequester the emissions from space rockets than it is to build a Lofstrom loop? Is it easier to synthesize jet fuel from the atmosphere than to electrify jets? Where should R&D resources be optimally allocated, especially if we're taking a risk that certain approaches won't work out?