irule for sorry pool and removing persistence on sorry pool

If you did not have persistence you could use priority group for that:

https://support.f5.com/csp/article/K7065

With persistence, the only option I see is iRule (or LTM policy):

when HTTP_REQUEST {
   if { [active_members APP_HTTPS_pool] < 1 } {
   persist none
   pool sorry_APP_HTTPS_pool 
}

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