No easy solutions.
I'd guess the highest priority should be on deorbiting (in rare cases, recovering, e.g. Vanguard or RTG-powered birds) the largest pieces.
That would do more to impede the chain reaction than sweeping up the smaller stuff. Need to first reduce the likelihood of more collisions like Cosmos-Iridium.
The smaller stuff is bad when it passes a certain density, but is far less likely to spread new, dangerous chunks into a wide range of orbits.
So lasers are out early on. Later they would be useful for mop-up. That leaves grappling, small attachable retro-rockets, drag balloons, etc. The technology is there. The will is missing.
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