I know how frustrating it is to "smart" a curtain after it is installed. Or even setting smart curtain tracks for a new home. Let's just say, I tried it all including smart blind controllers! The easiest method is to get SwitchBot Curtain but if you want something more permanent then consider a motorised smart curtain track from Zemismart.

If you are just not keen on the DIY route. I recommend the guys from HomeAuto.sg for a full smart home installation (one of the more affordable ones) or SoftHome.sg for just smart curtains and that amazing ripple fold curtain 04:44 is from them