For what it's worth, the Arm "alternative half-precision" format is not very different from IEEE binary16. The difference is that instead of using the maximum exponent value (0x1f) to represent infinities and NaNs, the AHP format uses it the same way as any other non-zero exponent, to represent normalized fp values. The tradeoff is that you lose NaNs and infinities, but you double the range of numbers you can represent (the max value goes from 65504 to 131008).

You have to select AHP by setting an FP config register bit, so (unlike bfloat16 vs binary16) it's a "for this whole chunk of code I am going to use this format" choice.