You can drill dozens of 10” holes through a concrete floor in a commercial office tower. The structural part of the floor are the tensioned cables inside the concrete, as long as you dont’t sever those, you can drill a ton of holes without impacting the structural integrity.
I used to work in concrete construction, doing post tensioned and SOMD for elevated slab. Coring might be simpler for SOMD, but post tensioned has such a high density of cables that I don't think it would work.
Could you run vertical pipes on the outside in back of the building, and run horizontal pipes through space between adjacent apartments that you specifically leave for that purpose when converting the interior?
If you need intermediate pumping stations or holding tanks due to the height of the building, those could be inside adjacent to the outside pipes.
