But that's the problem. The debris disperse whatever heavy metals and compounds into the atmosphere. Removing the debris and taking it somewhere, even just landing them protected in a heat shield, could reduce those vaporizing particles, if those are going to be a problem.

Eh... no, not really. At low altitudes (<500 km), sure, but much above 600 km you are starting to look at decades for a passive deorbit depending on solar cycle and ballistic coefficient.