The NGFW supports automating almost everything through the API. Here is a process to script uploading and installing dynamic updates -> https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000PLfrCAG.
Using the API Browser (see the link on the bottom of the above URL), you can figure out how to modify the script for software updates.
What's not mentioned in the docs is enabling API access -> https://docs.paloaltonetworks.com/pan-os/9-0/pan-os-panorama-api/get-started-with-the-pan-os-xml-api....
@Bad_GoatSorry! Not meaning to be a smart alec. I probably should have mentioned this solution first as long as you don't mind working on the scripts. Otherwise, the Panorama method will be easier.