I like the idea, but what kind of requests/demands would you want them to make?
I dont want to see them be like the democracy mandates, not just because they are tame but because they can be impossible, how do you construct 4 mining stations when there are no unclaimed star systems?
Neither do we want them to feel repetitive, so there need to be quite a few for each of the 8 factions.
Having said that, lets brainstorm a few possibilities to get a better idea of specific what we want to see.
Peaceful:
-Sign NAP with someone (could include a check to see if anyone is willing to do this, or specifically target other peaceful empires)
-Sign white peace in a current war (refusal could increase your WE depending on faction strength)
Warlike:
-Declare War (could include a special case humiliate CB or a new type of CB)
-Insult enemy
-Break NAP
-Increase fleet limit/size
Xenophile:
-Sign migration treaty
-Join federation, become an associate or get a new associate to your federation
-Increase trust (or opinion) with other empires by a certain amount
Xenophobe:
-Break diplomatic ties with other empires
-Enslave xeno species
Spiritualist:
-Build new temples, or upgrade existing ones (should ofc check if you have enough planets without temples, or upgrades available)
-Would love to see something about 'converting' pops to spiritualism, but we don't have any direct way to do this properly as of yet, maybe with a future diplomatic update
Materialist:
-Research tech (make a, perhaps random, tech available to be researched guaranteed to show up as an option and you have to pick it or fail mission)
-More research/robotic jobs (just like temples, check if possible)
-Build megastructure (more for late game, but could give a speed bonus to build said megastructure)
Authoritarian:
-Resettle pops (should mostly be if any planet has overcrowding/unemployed and planets with jobs/room)
-Vassalize enemy
Egalitarian:
-Liberate planet (should probably check if a planet is unstable, or have lots of slaves, or perhaps just owned by authoritarian empires)
-Reduce unemployment (again only if possible to build more districts/buildings on said planets)
A lot of missions/requests would make sense with a wider range of diplomatic options, that we hopefully would get one day, like influencing other empires with your ideals.