We use the URL Table to pull an internally maintained blacklist of IPs across all of our firewalls. Is it possible to add a "Port" Table as well, to pull a list of dynamic ports into an alias?
Maybe the API would do the job for you. You can install the addon on the firmware plugins.
os-firewall
https://docs.opnsense.org/development/api/core/firewall.html
Then you could setup a call which would update your Alias Port list.