If your grandad is too challenging for a residential home with a team of staff on duty 24/7 he would still need a skilled team of carers anywhere else. One carer would be on duty from 8am - 8pm (for example) maximum, with probably a 3-hour break. Then you've got the nights to cover, so really you would need at least 2 carers 24/7. Also they each need their own private bedroom and a bathroom not shared with the client, with the ability to have 8 hours regular undisturbed sleep.
In addition, I would add that, although there may be some very rich people who can pay for a team of live-in carers, this is actually very expensive. In a NH all the clients are sharing the total care costs between them.
In a home environment, how would you keep both him and the carers safe? They can't restrain him if he wants to go out of the front door. If he is aggressive then the carer would probably decide to leave and very soon the agency would advise that he is not a suitable client for live-in care.
Carers must feel safe. I have talked to some of my mum's carers who have worked for aggressive clients. If you have to sleep with a chair jammed against your bedroom door, or have been attacked, or just sworn and shouted at, you don't choose to return to that client. Most live-in carers are women, and I can't think of many women who would choose to look after a male client with challenging behaviour.
Forgive me, but I don't think your plan is in your grandad's best interests. He needs the right secure nursing environment. From what you say, he is now too ill to live at home.
