Yes, you can.
True Polymorph only states that:
The transformation lasts for the duration, or until the target drops to 0 hit points or dies.
The steps in practice are:
- Convert Creature into Object
- Use object as consummable material components
- Consumption of material effectively reduces object to 0HP(my logic, no official ruling but a destroyed object logically needs to reach 0hp)
- Spell completes and object reverts to it's original creature form.
You now have both a completed spell and the original creature.
When should the creature revert?
The key aspect here is that the creature doesn't revert until it reaches 0HP, which is after the component is consumed. If it was before, then the component wouldn't have been consumed, the spell wouldn't have been successful, and the creature therefore would still be an active object.
Will it blend? Specific beats general.
The question of what consumed means is a sticking point. If the consumed material is absolutely destroyed, what does that mean and does it actually matter?
We know that consuming the component destroys it, but does that mean it's destruction preempts the specifics of true polymorph. In this case, the specifics of true polymorph would override the general consumption of components.
Permanency resolves conflict
If made permanent, then you're just dealing with a material component full stop. Use as needed.
9th level spell slot to create a component
Those who have access to 9th level spells likely have access to hard to find or expensive components. Utilizing this resource seems reasonable.