Extract indexed URLs from Google CSE? | NewProxyLists

Hi guys, I need to know if it is possible for other users to get the URLs used by a Google custom search engine.
I got a list of links with 500 websites and I want to put them in a CSE.

My fear is that other visitors will extract them and maybe clone the CSE.
I know that everything is technically disposable, but also, are there other methods known to the public to obtain index pages of a CSE? (Github Scripts, Software, PHP tricks)?

Is there maybe a better way to build a custom search engine without Google?