The pine64 position on binary drivers is not as hard as the purism one (perhaps they try to balance more with cost), but there are still projects to reverse-engineer and replace some non-free firmware, such as the modem firmware: https://github.com/Biktorgj/pinephone_modem_sdk.
I agree that Fuchsia will become a problem going forwards, even if Fuchsia drivers can be reverse-engineered. It's also possible that phone hardware is commodified enough that google will be unable to lock us out, or that google abandons or delays the Fuchsia project.
The PinePhone has the same security properties as the Nokia N900 where the modem is connected over USB rather than an interface with direct memory access (eg: PCIe) where the proprietary software running on the modem can read anything in main memory.
I agree that Fuchsia will become a problem going forwards, even if Fuchsia drivers can be reverse-engineered. It's also possible that phone hardware is commodified enough that google will be unable to lock us out, or that google abandons or delays the Fuchsia project.