Securing custom rest API endpoints with public access from PWA

I’am trying to implement a headless woocommerce based PWA on ionic angular stack. I’am now accessing the woocommerce rest endpoints by using client id and secret. To make it more secure iam writing proxy custom endpoints in my custom plugin. But I need a way to secure this endpoints as some of them are publicly accessible by the PWA.
Can someone suggest best way to do this ?