Because these are only flags and 8-bits are reserved, I would simply use a uint16_t and a uint8_t. The Pulse Oximeter Profile document I have is from 2015. The specification is stable. Unlikely the additional flags will be needed anytime soon. Even if, you can then pretend the flags are separate. The central will see an array of bytes anyway. The struct is just a nice way to access each element.
I believe the first character needs to be a zero 0.