Copilot Pro as a separate offer is no longer available. The consumer Copilot Pro plan has been discontinued. It was replaced by Microsoft 365 Premium, which bundles Copilot app features with a Microsoft 365 subscription.
https://www.microsoft.com/en-us/microsoft-365-copilot/pricing/individuals
You can purchase it by following the Buy Now link on that page
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hth
Marcin