If what worries you is the price, they are dead cheap at bike 24

have a Venge Vias disc myself- You can use any bar and stem combo with the standard fork and bar width (i.e. not Giants smaller diameter). Only difference is that you won't be able to route the cables internally without the Vias stem, as the cables run through the steerer tube. A lot of pros used aftermarket stems (usually the over sized sprinter stems) with the Vias frame to save weight and/or increase stiffness.

I personally really like the aerofly bars with no rise (they are light, stiff, and aero), so I'd recommend keeping those if they come with the bike (the riser bars aren't ideal IMO- I'd rather run a less negative stem then have that rise). You could put on separate aftermarket bars though.

Thanks!