Honeywell say GLS is optional on the 737NG, and it is a function of the FM, not the aircraft (Hence Honeywell).
It is actually solely a function of the MMR on 737NGs, which is capable of doing that since around 2004. However you do need the required hardware interface, nav panels that support entering a channel number instead of a frequency. That panel might be an option, didn't cost us anything though as boeing was quite eager to get it out into the market.
But back to the original subject, I haven't had much involvement with the 737NG, but I'm reasonably sure it has a dual servo autothrottle - something that I'm sure will be carried over to the MAX.
Yes, it has dual servos, which is needed for OEI CAT III approaches in which the autothrottle drives only the thrust lever of the remaining engine.