The biggest problem with the Voice in my eyes is people don't understand how our constitution works.
The major issue is people envision the constitution as being akin to the US constitution. While many of the ideas are based on the US constitution, we did not have to rework the source of power and legitimacy from the crown to the people.
So our constitution is more a definition on what the three tranches of the government can and can not do. There is no bill of rights as we as Australian can still draw our rights all the way back to before the Norman Invasion.
So, the Voice. Introducing the Voice requires modifications to be made to s51. This outlines what the Federal Government can legislate. At the moment s51(xxvi) aka the Racism powers was created to allow White Australia policy. It was far later used to take responsibility for Aboriginal and Torres Strait Islander away from the states.
Now I argue that s51(xxvi) can create the voice right now, but the Racism power is a rather horrid provision. It is only now used in what can be concidered positive way, but the argument to strike the power is a good one. A better way is for a new provision enabling legislation for First Australians with consulting with the Voice.
But no matter how the Voice is added to s51, it does not force parliament to enact laws, only it can do so. A Voice can still be removed or defunded by parliament.
Adding permanent funding and powers via constitution breaks the purpose of the constitution