There's no government layer at the level Debian operates. As pretty much everything internet based, its users ( and contributors) are international - which I think is the main reason why we don't see public alternative services to social networks, search engines, etc.
China is a special case, since they explicitly would rather keep the userbase restricted to Chinese citizens.
There are tons of federal agencies that could sponsor FOSS.
https://www.usa.gov/federal-agencies/
I'd love to see a program where FOSS devs could get say 2k-4k tax free per month depending on part or full time work. A billion a year would pay for just under 21k developer years or close to 42k part time devs.
Federal, state and local governments burn some large integer multiple of that amount every year on proprietary, closed source software.
probably not an integer, more likely an irrational number
But, perhaps you were joking and it's an 'irrational' amount?