Something that would be nice and related to server templates, but not the same, would be something like 'snippets'.
Basically, snippets of commands that could be inserted into any deployment script.
E.g. If I made a 'docker install' snippet. I could insert that snippet into deployments by selecting it for either the pre-deployment or post-deployment section (or container section).
Allowing adding multiple snippets and selecting the order (either before the section is run or after).
Could have other snippets like 'ufw/firewall config' for example.
Basically, like legos we can create and then re-use them for different deployments. There would be the additional benefit of being able to update snippets for all deployments from one location.