Requiring a city to have certain improvements in order to be allowed to build particular units is possible. The template even comes with a
code generator for that kind of code (note that I changed the template file structure a bit since I made the linked video).
That's very interesting. In my case, I would really appreciate that just because tanks exist they can't be produced at the front in a FOB. Also, since you have to choose between 3 factories after the regular one, you would have to alays choose between Armor factory for tanks, missile factory for missile ammo, aircraft factory for planes heli or drones. You wouldn't be able to have it all in one city. Conscript units would always be available, Regular infantry when the first factory exists (Ammo factory), Advanced Infantry when the Manufacturing plant follows up (named Weapons Factory). Another idea is to reuse more city improvements, that are most probably useless in the last 3 governments. Courthouse is not really that useful except for a Democracy which is unlikely to hold, and would most likely only be needed for the west (I'd obviously like Russia to use Communism (or Martial Law or however I call fundamentalism which allows "fanatics" conscripts units and no discontent people). So Tribunal could be a west dedicated "NATO Headquarter" and when a city has both NATO headquarters (which still wuold act as a courthouse for the west entities) and an Armor Factory, it can produce the NATO delivered tanks (say, Leopard, Leclerc, M1 Abrahms) when the required tech is researched. There are a few city improvements that can both act as their original and be used for scripting for escalating the war and the use of diverse units. An Airport + Aircraft factory would allow planes, while without the airport you'd have only drones and helicopters. Maybe production of a forward hospital (I saw a Bus transformed into an improvised military hospital, I think it's a cool idea) could only be done after you built a Hospital which i consider the Temple with +1 happiness when "Red Cross help" is built as a wonder (available for both countries). Similarly, a Shipyard (Port Facility) would be required to build military boats. Sure they'd be veteran right away so I'd have to be careful of that, but that would avoid a FOB placed along the water to produce a gigantic battleship.
Just to make it clear, there would be
Ammo Factory > Weapons Factory
then the 3 options (replacing the 3 regular options to elevant to the third factory level)
Armored Factory
Missile Factory
Aircraft Factory
And behind is the Recycling center.
BTW: Recycling center could be available later (pollution would be an issue early on) and named "Advanced Factory" and conditional to produce futuristic units (say if the F35 went to be produced, the Su57, hypersonic missiles becoming a norm etc)
Military Shipyard
Military Airport
Barracks would be Military Academy
I am trying to keep the terms similar so not to loose the player. They would understand that Factories go together, and "Military" are unit oriented improvements. They would all conditions what you can build.
Regular imrpovements
Government Center
Granary could be Grain Silo but I have an Idea to name it UN Help something
Hospital > Football Stadium > Music Arena
School > University > HiTech Research Lab
Permit for Village > Permit for City (aqueduct/sewers)
Marketplace > Mall > Bank
Highways
Maritime Center (foir offshore)
Fishing port (for Harbor)
Tribunal (courthouse) TBD cause I have ideas about this one
Noteworthy wonders (note: eventually i'd like to rename them all in cyrillic so they give a cyrillic vibe to the cities. The improvements would stay in english for practical reasons. Some units would be named in russian and in ukrainian maybe as long as it's close enough for english speakres to understand.
Bolchoi (michaelangelo) replaces Music Arenas in all cities
Folding@Home replaces SETI (up for grabs)
"Electricy" doubles Football Stadium (maybe TV retransmission/sports)
Oblasts (Pyramid) in moscow so that russia has advantage on foot shortage thanks to its oblats and republics. Ukraine needs to build the Silos, renaming them UN help would simulate the fact there is more food help delivered from outside the country in ukraine, than in russia which does it by itself.
Red Cross would be neutral and double the ffect of "Hospital" and up for grabs
Hanging Gardens > Red Square, more happiness in russia than in ukraine at least to simulate the government seems in control while ukraine is in a state of warzone.
Magellan expedition > Chernomorskiy Flot in sevastopol
Isaac Newton's College > Kurchatov Institute in moscow
UN in nato/neutral of course
Shakespeare's Theatre > Free Pr0nHub as placeholder until I have a good idea of something that would make everyone unhappy happy

during WWII hitler gave the first amphetamines to his population so they were "happy" but that's in the past, that's the closest thing I could think of that can make everyone unhappy "happy" unless going SciFi
I'm thinking of adding something to the recycling center. I don't think recycling is a current requirement along the front so sure it would act as a recycling center, but it could be renamed and allow for something else too.
Checking the wiki of the ukrainian factories, they are spread along the country. I know they are building some at the moment in the west obviously. And I wish we had more of this information on the russian side which must have very specific factories too (Its hard to find the same level of info for the russian side without speaking russian). Altternatively, their factories might not be all near the front either. For ex Kazan is where Tupolev builds its aircraft with the Kazan Aircraft Production Association KAPO factory/industry. The TU160 and the "new" Tupolev airlines come from there. Just an example (Kazan is off the chart although not too far east. It could be put on the border).