Are all major custom fuel types (gasoline, natural gas, coal, kerosene/jet fuel, propane) available in synthetic, with little to no modification of the hardware using it, and able to scale to immediately cover our global usage?

Yes, because you are simply exchanging the "basic" ingredient "crude oil". All refineries basically need some simple temperature and production process changes, and bobs your uncle.

And there is less modification needed. Back in the GDR when the Trabi with it's two stroke engine came to market, they made some Tests with a Lloyd (basically the same concept but from West Germany). Somewhere along testing they has major issues with the Trabant engine throwing rods everywhere after a few 1000 km - for Testing, they used the West Germany Oil instead of soviet. The production process was similar, the crude oil however not. It had a lot of contamination that made combustion very bad. 70 years later, a lot of this is being treated in the refinery, but there's still lots of unwanted stuff in most fuels, be it Diesel, Gasoline or whatever (one of the reasons, why additives are needed).

A few auto clubs did Tests in Germany and Europe over the last 2 years with those fuels and found, while the co2 emissions do not change (why would they, the co2 neutrality is being delt with in the production of the fuel), other emissions reduce dramatically. AIRBUS did Tests with so called SAF (sustainable air fuel) and they found that NOx and soot emissions where reduced by over 60% at crusing altitude. Mazda tested the new 6-Cylinder Diesel they developed with such fuel and they found, with all the filters and stuff, there's basically only Co2 and some hydrocarbons leaving the tailpipe.

Basically, there's still lots of crap in the fuel from the crude oil, that can't be refined out properly.

As for the scaling, yeah in theory it would be possible...but there would be a huge need for subsidiaries - making production dirt cheap, so those greedy fuckers in the oil companies still get their expected rate of return. In Europe that's influenced heavily with the carbon tax getting more and more expensive and customers not paying 3 Euros per Liter...

Why 2030? You just said you are advocating to ban them now.

I am. But it would need all world governments to unite - so theoretically absolutely possible (remember CFCs?), practically in this political world environment? No.

So you need countries to "go the long way" doing it now up to 2030 (so production capacity can ramp up) and simply forcing the fossile competition out of the market by being cheaper.