To sequester 1 gigaton of CO₂ (about 2.5% of global CO₂ emissions in a year), you’d need billions of tons of rock and an area of land approximately 6 X the size of India (rough, shit calculations, lots of assumptions)

That rock has to be mined, moved and ground to a fine powder, spread over 30milliom kms and then given time to react and hopefully not leech into waterways where it can fuck with alkalinity and ecosystems