I'm aware of Astroscale (https://astroscale.com/). They're a Japanese company with a presence in the US and UK that's commercializing this sort of service. I'm not sure if they have plans for multi-satellite de-orbit services, but they do have single-satellite plans.

Among other things, they're promoting a standardized docking adapter (https://astroscale.com/docking-plate/) to give satellite operators a path to either life extension (refueling and/or orbit raising) or de-orbit.