

It’s very likely that no amount of negative feedback will change anything. Why not waste some of their time anyway? Write to them, call them, spread the word. This is the only thing we can do. Even if it goes through regardless - at the very least we can make it as unpleasant as possible.
As of right now, it’s looking like GrapheneOS will be unaffected, and Google has yet to lock down the bootloader. So this should remain a valid option for at least 2 years.
Other than that:
Honestly there probably isn’t any good, long-term solution. Personally I’m somewhat shocked we’ve gone this many years with reasonably open smartphones. Next step is probably closing bootloaders in new laptops, as part of the switch to ARM (which is already undergoing).