Wildcarding json keys in json query

PG 11.5 on linux

Let's say I store a jsonb in a column called test_results that looks like this...

{

ports : {

    port_abc:{min: 5, max: 7, mean: 6},

    port_def:{min: 5, max: 9, mean: 7},

    port_ghi:{min: 6, max: 10, mean: 8}

    }

}

And I want to to get all the port names where the mean is >= 7.

This works...

select 1 from mytbl where cast(test_results#>'{ports,port_abc,mean}' as float) >= 7 ;

But I want all the ports that have mean >= 7.

Something akin to...

But the "*" doesn't work :-(

Any ideas ?
Thanks!