To be completely fair, I still keep the standard Ganyu Freeze DPS build and she would still work fine as a support. With this, I have the option to use her as a sub dps even though you already have an Ayaka in the party.
If you don't have time to build her Blizzard Strayer artifacts, then stacking ER should be enough just for her burst's Cryo buff. So do continue with your Noblesse if that's the case.
Though in case you're curious about building DPS Ganyu alongside Ayaka anyway, then you have two choices: Wanderer's Troupe and Blizzard Strayer.
Wanderer's Troupe deals bigger raw damage with her charge attacks, as well as Melt, but it is very difficult to build because you'll need a lot of crit rate for consistent damage.
Basically, go Blizzard Strayer if you want an easier time in building her as DPS.