Thanks for the input... annoying that I'm doing this just before the Sensah and Ltwoo hydraulic groupsets are released. The option of the cable actuated hydraulic Juin Teck GT-F's is an interesting option (external cables could be neater than external hoses), but there is a price to pay for the GT-F model.
I will also look out for discounted or second hand Sram groupsets, but my budget is very very tight after buying the wheels, frame and powrlink pedals. I'm trying to build a light titanium gravel bike for USD $2,500. I'm already at $1,600 for the frame and wheels.