I have been watching out side coverage of the game and reading up on the lore of the game, I do look forward to the full release of the game when it hits other retailers. My love of Xcom 2: War of the chosen is the reason my attention was drawn to Phoenix Point. More I learned about Phoenix Point lore it made me realize you have a story that is extremely interesting than Xcom or other turn based games out there. I only wish to make a few suggestions to help flesh out things.
The way New Jericho and the Children of Anu are presented makes them seem as complete opposites. In the sense that should humans choose Technology to save them selves or Biology. Right now Children of Anu seem to have the most fletched out of the two.
For New Jericho I would suggest pushing them into splinter factions where one group will build Terminator/ Space Marine Dread Naught type troops. People who willingly put their brains in machines giving up what makes them human in order to destroy the virus.
Other splinter faction of New Jericho being people who develop a religion around fire. Seeing it as it being pure and going out of their way to burn non humans. This faction could offer allot in regards to unique elemental technology. Using cryo weapons and plasma based weapons to scorch earth away the virus. It could lead to interesting technology like lightning technology that bounces between enemies or napalming areas.
As a whole New Jericho should gain access to things like forward observers as a class. Being able to call in air, mortar, or artillery strikes . Or have a class that solely focuses on calling in big area strikes if you have appropriate vehicles/ weapons.
Synedrion as a concept is really good. Infiltrator class makes sense, in that a group of people who do shady things would develop a class out of their own paranoia.
The concept could be taken in the sense of first responders. Where when Synedrion deploys their troops they send a force in and their troops air drop in behind in enemy lines to help evacuate civilians. An example being a class built around being a combat medic who drops in a area (rng based on winds and location) with a highly advanced drone run by one of their A.I. who protects the medic.
Then there could be a group that Synedrion considers expendable who might be rebellious youths who want to act out. Using drugs or tech that Synedrion stole from Children of Anu and New Jericho that enhances them to super human level but runs the risk of killing them.
Children of Anu I have nothing to say about their story over all is really interesting and I look forward to learning about them.