Thank you for reaching out and posting this question!
Locksmith is definitely the app I’d recommend for locking specific pages and it’s very easy to use. If you run into any issues or require any assistance using this app, the app developer is always available to assist you - you can always reach out to them directly through the contact information found in the Support section of their app’s page.
Did you get a chance to try out Locksmith on your shop? Or, try locking the page through the app’s interface?