For mental health, regular conversations (e.g. via phone) and occasional visits ought to work.

Is there any service or something that offers such things? Cameras to them seem very intrusive

Service? I didn't mean conversations with or visits from a stranger. That's moot. The closest they are to the person(s), the better. I was thinking you / your family calling them regularly, but it seems like you might not have a great relationship.

I feel like I'm lacking a lot of context to give you useful advice.

How about asking with more context at Interpersonal SE?

https://interpersonal.stackexchange.com/