Nuclear reactors and solar panels are too easy for energy, next is probably going to be the cargo system so no that won't be added cause it'll inflate the economy far too much by automating everything

as Meowsalod mentioned, miner android and other sf items that are removed would cause automation or an unfair advantage to those who would grind them

Everything removed from Nations was considered and has been intentionally removed. Towny is the server for Slimefun industrialization, though I wouldn't recommend creating any elaborate industry there since a new towny server is in progress.

Side note though, I'd be willing to add brand new machines or Slimefun items if you have any in mind that fit Nations.

I think that miner androids could work if there is a restriction on them e.g. one per person.

Miner androids are not on the table, no matter how many restrictions.