The final methods seem equivalent to reading a non-float binary fractional number .xyz... from a random bitstream and stopping at the point where further digits

The final methods seem equivalent to reading a non-float binary fractional number .xyz... from a random bitstream and stopping at the point where further digits will be truncated in the float representation. eg if x = 1 read 53 more mantissa bits and stop, if x = 0 decrement the exponent and repeat. There's no bias in such a process.