Figuroz Connecting the device during boot doesn't pose a threat your data, because at that point, all of your data is encrypted at rest before the first unlock.
The threat model of that feature is to make it so someone can't connect a device to your phone while it's locked and data is not at rest. This doesn't come into play until you unlock your phone the first time after a reboot.
The moment you reboot, the data is at rest again until you unlock it once more etc.
GrapheneOS also provides the auto reboot feature for this exact reason. You can have the phone reboot after a set amount of time to place your data back at rest.
Furthermore, On GrapheneOS, you can "end session" for secondary user profiles while the device is still running to put that profile's data at rest without having to fully reboot the entire device.