Easy way
On the left panel
Click "online store: then at the bottom click ":preferences"
Lower down in this page - scroll down -- you will see the option : 'Restrict access to visitors with the password"
Tick " activate "
Now if visitors com to your shopify page will see the notification
IS COMING SOON - and under it " log in with password "
This a simple way to hide that you are open and also to restrict who is able to see content/products or order etcetera
note: still if you want someone to be able to see and order- as normally when your website is up and running - give them the password
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