the three domains ic0.app, ip0.io and icp-api.io behave the same for API calls (query, update, read state, status). In your case, it doesn’t make a difference whether you use one or the other.
There is however one difference between icp-api.io and the other two domains ic0.app and icp0.io. icp-api.io only serves the API endpoints, whereas the other two domains also serve the service worker and raw endpoints for the canister subdomains (e.g., <canister-id>.ic0.app).