We live in CT. My parents probably do not qualify for low income programs. My mom is trying to find out if family caregivers can get paid through Medicare etc. My son is 18 and has been watching his grandpa while grandma runs out to the store or for prolonged periods of time. My dad had several strokes and has aphasia. His brain and speech were affected. He was a tool and die maker and engineer. His mind still wants to create and work on projects but he gets obsessed to the point of injuring himself. He doesn't need help with bathing or eating although he will sometimes go without eating or drinking for days which is another issue. We just need someone there to watch him to make sure he doesn't do anything stupid with power tools or try to go up a ladder.
Grandpa can pay him from any assets he has. This would also provide "proof" that the expense was directly related to his care and not a "gift". So make sure the amount paid and the hours are reasonable. Although with dementia and what you have described it sounds like he would need, or could use, a caregiver for several hours daily to make sure he is safe and is eating when he should. So if grandma can have a set schedule when a caregiver is needed that would be best. (example M, W, F from 9 am to 4 would give grandma plenty of time to run errands and have some time for herself)
If Grandpa is a Veteran he may qualify for a Home Health Aide from the VA.
Depending on circumstances the VA might pay your grandson to care for grandpa.
BUT what happens when school starts? Your 18 year old should NOT give up school to care for grandpa.
and I have to add.
This should only be done if your son WANTS to sit with grandpa and care for him. He should be with friends, he should not be expected to care give for grandpa.
Would grandpa actually listen to your son if grandpa really wants to do something he should not do and your sons says, "no, you can't do that" . Is your son strong (not physical strength) enough to redirect and keep grandpa safe? Is this a responsibility he should take on?
Who will carry the "guilt" if something does happen and grandpa gets hurt?
Even if he was able to get paid, it wouldn't be much. I think the best thing your son should be doing is going to school and getting himself a good job. He needs to start being independent and starting a new part of his life.