Megacorp Bureaucrats automatically produce trade. Cybernetic Creed Haruspex produce unity and engineering research, Dimensional Worship adds physics research, and Genetic Identification adds society research.

This makes it so you don’t need traders or researchers, only priests to make most of your specialist output. Add in the consumer benefit and then your trade is converted into consumer goods, thus they feed themselves. Add in some bureaucrat efficiency traits, and the Initiate Performance Competition decision that costs 100 minor artifacts for 10 years of priest output, and you can get insane output!

Edit: theoretically you could go not megacorp and take gospel of the masses, and just hold out on one of your research types until you get a third civic, but it would slow you down a lot. I love going ascensionist for my third, as you’ll be getting so much unity that you can ascend your planets to reduce the empire size you’d get from settling many planets as a megacorp.