When you don't know what keys to observe for a CP, you can use a macro that determines the keys at runtime.

cp-macro.js

export default function makeComputed(objKey) {
  let keys = Object.keys(get(this, objKey))
    .filter((key) => {
      // choose the keys using some logic
    })
    .map((key) => `${objKey}.${key}`);
  
  return computed(...keys, {
    get() {
      // do stuff
    }
  })
}

export default Component.extend({
  myObject: { ... },
  stuff: makeComputed('myObject')
});