Will my home network become a target for hackers if I run a bitcoin node or run bitcoin mining from devices in my home network?
Would a VPN help or is it better to run bitcoin node / mining in a completely different network?
I would say that every online service carries an increased dose of security risk. I would advise you that if you don't know much about online security, it might be better to give up on that idea.
if you still want to start your node, it is certainly ideal to do it through another network, or at least not the ones through which you do other personal things.