All science is materialistic

[HappySkeptic]

One of the other difficulties is that under quantum theory many of the conservation laws are NOT absolute. The uncertainty principles allow for some limited 'flexibility'. For example, energy conservation can be violated for short periods of time. Momentum conservation can be violated if position is narrowed down sufficiently. And, in fact, one of the properties of 'virtual' particles is precisely that they are 'off-shell' and hence violate some of the conservation laws.

True, at the quantum level.

Conservation "laws" come about because of underlying properties of the universe.  Like the laws of thermodynamics, they are emergent properties, not a-priori ones.

Noether's Theorem

The symmetry of flat space relative to translation leads to momentum conservation.  The symmetry relative to rotation leads to conservation of angular momentum.  Forces which can be modeled as the derivative of a scalar potential lead to conservation of energy.