A new religious movement has arisen in the galaxy, valuing austerity and simple living and generally shunning the modern and galactic way of life. The most committed members of this movement have embarked on journeys to hitherto unknown sanctuary worlds (~5% of the galactic population starts a minor civ and creates transports leaving from core worlds of existing divs, moving to new worlds with strong boosts to Influence, Tourism (pilgrimage destinations), and Planetary Defense (reclusive), but with sharply lower military and social production. This civ would have powerful Diplomatic, Influence, and Tourism technologies to be traded with, or its rich sanctuary worlds could be conquered.)
Minor civs have no influence, therefore this new civ would have to be a major civ if influence would be one of its strong points.
The galaxy has recently been subject to a bout of coup plotting. Corrupt generals in a number of starfleets have commandeered vessels with the intention of occupying homeworlds and forcing a change in government. (Each major civ will have a corresponding minor civ, named "[civ name] Coup", armed with transports and various vessels aiming for their homeworlds. If a successful invasion of the homeworld takes place the government system will be reverted back to Imperial and secondary revolts will take place with a probability of 1-(influence percentage on planet * approval rating on planet), with the probability then halved for Benevolent civilizations and doubled for Malevolent ones. Revolting planets will start their own major civs, which can influence-annex each other. Additionally, the player will lose control over the home world for 10 turns, with this amount doubled for malevolence and halved for benevolents.)
So far that's not possible, as there are no government systems or politics. But these things could be added in a future expansion (I hope), alongside with the major events.
But I really like your ideas, and I hope that devs add something similar to them.