Seems you have to be current on your account to port your number. They aren't, but they also are unable to use Google payments to become current.
This is illegal:
“Once you request service from a new company, your old company cannot refuse to port your number, even if you owe money for an outstanding balance or termination fee” [1].
Author should report Google Fi to the FCC once the government is back online.
[1] https://www.fcc.gov/consumers/guides/porting-keeping-your-ph...