I'd contend there is one good idea in this thread, which is to consider changing the default victory condition away from conquest.
Conquest has two problems as a victory condition:
The point at which victory becomes impossible for a defeated player occurs well before the victory condition will force their capitulation. Therefore you are essentially relying on the good will of the defeated opponent not to drag out the game and waste everyone's time. That choice feeds trolling and toxicity in the community. (Admittedly 0AD is much better in this respect than most of the Age of Empires games because it has the territory mechanic, which encourages major military defeats to cascade into a complete civilizational collapse more rapidly. But it is still a problem.)
Conquest discourages multimodal gameplay. The only thing that matters at the end of the day is who is better at killing enemy units and buildings. That means some aspects of the game that some players might find enjoyable, such as building a diverse, attractive, and defensible city or constructing effective resource extraction and trading operations, don't actually improve their chances of victory unless there is a parity in basic military competence between the contestants. A completely pacifist player will never win a default match of 0AD, even if they have 10X the economy and territory of their opponent.
If I were trying to devise an alternative, I'd probably go with a victory-point contest based on territory controlled. Players get victory points for the total amount of territory they own, plus major bonuses for having civilizational monuments like temples and wonders. Eliminate players when they have less than 1/3 the victory points of the next highest ranked player.
This game mode would appeal to a variety of playstyles. Boom oriented players could race to carve up the whole map as fast as possible. Eco turtles could plow resources into monuments to keep parity, and perhaps ultimately drive to victory as a miniature cultural powerhouse. Militarists would steal territory. Balance would hang on the territory radius of buildings, and the VP bounty vs price of monuments.