The smallest footprint for an actual scripting probably will be posix sh - since you already have it ready.
A slightly bigger footprint would be Python or Lua.
If you can drop your requirement for actual scripting and are willing to add a compile step, Go and it’s ecosystem is pretty dang powerful and it’s really easy to learn for small automation tasks.
Personally, with the requirement of not adding too much space for runtimes, I’d write it in go. You don’t need a runtime, you can compile it to a really small zero dependency lib and you have clean and readable code that you can extend, test and maintain easily.
Isn’t Ubuntu Pro basically just an extended support for a set of universe packages for their LTS versions and free for private use?
How is making enterprises pay for extended LTS because of corporate no-update-just-insert-coin mentalities even remotely close to ransomware?
Like I get everyone who doesn’t like Ubuntu for various reasons, but this sounds completely dumb to me.