Can someone explain the new outpost actions to me? I am playing as the Riftborn, if that matters.

They seem to have changed sometime in the last 6 months (yeah lots of time I know) but I can't see anything in the patch notes for the UE, Horatio, or even Riftborn updates.

The -stealing action is still there as before, but what are the two -boosting actions for? An outpost is not able to produce anything, so what is the point of boosting  by 100% or 25 flat for 10 turns? (also, two actions are called the same - Greener Grass)

I did a search of the forum but got zero relevant results.

Riftborn do not use  to grow their population, so they use  to grow up their first population unit instead. Outpost does produce (and consume) resources.

That is a very good point, I forgot about that.

So that means that the -stealing action does not directly benefit your outpost but merely harms other outposts?

Yeah, it probably doesn't. At best it enables manpower growth, but doesn't boost population growth.