There should not be an issue. All the work today is on IP cameras. You didn't share much detail but the old non-IP 2.4GHz cameras were not so much hackable but subject to easy to interfere with.
That is only cured by get the cameras wired.
I'm thinking of getting a wireless CCTV system that will not be connected to the internet. Knowing that wireless items can be hacked, how can I reduce that possibility with this type of system? I've found tons of articles that deal with internet connected systems, just none that specifically deal with non- internet systems. Thanks!