The approximate-GEO belt involves far fewer satellites than projected megaconstellations, in a far larger volume of space, travelling at far lower orbital velocities, with a much tighter orbital plane distribution (so even lower relative velocities). Their orbital planes intersect every 12 hours instead of every 0.75 hours.

Targeted space junk disposal in GSOs appears to be quite practical. The easiest major orbital changes for an SEP stage to burn, structurally, involve lowering periapsis from high orbit.