Install in parents home

Hi
New to HA but wanted to ask if below is possible
Set up HA in my home on Raspberry Pi with sensors etc and post all equipment to my parents home. Would I need to set up anything in my parents home or will it just plug and play? They don’t have internet and I wanted to post items so need to make it as simple as possible for my parents.

Depends what “sensors etc” means.
If they are using wifi and has hard code IPs then it will be problematic.

But if they don’t have internet, do they have a router?

HA OS is not really usable without internet access. So stick with HA Container or HA Core (venv)

No they don’t have a router. I am guessing there is no smart home solution unless have a router ? If I get them set up with internet and router can I still post to them or will I have to configure so works on their Wifi ?

You could buy a used router for next to nothing and it will do the job. Not sure if it’s even required.

But I don’t think I would install a smart home remote. If it’s only temperature sensors then it would could work but anything more then I would probably not do it.
What is the “goal”?

motion sensors to switch on lights. routines for bedtime and morning. door sensors.

Ok… That is in my opinion too much for a remote install.
I would not do it, it could be very annoying if something stops working in the wrong state and you can’t access it to change it.