Custom campaign?

As in, I want scenarios to have the same homecity, that progresses as the campaign progresses.

You must create a mod with a custom civ which has its own home city. But I don’t think you can recreate the card progression system of the main campaign.

Let’s say I make a series of scenarios. How could I upload them as a campaign?

Same. I think it’s possible with a mod which links all your scenarios.

Unfortunately, today the scenario folder is outside the game files managed by the mods.

It’s something that could be fixed with this: