Redirect users accessing our app from a geo-blocked location to a URL which specifies the blocked response page to notify them that they are accessing from a geo blocked country

Hi,

You should be able to achieve it using iRules. You can create Data Group of list of county codes that you want to block and apply that Data group in iRule. Once it is matched, you can redirect request to the required response URL.

You can refer below article and modify iRule as per your use case.

https://support.f5.com/csp/article/K43383890

Hope it helps!

Mayur