Interesting topic, reminds me a lot of the fantasy series “Earthsea” by Ursula K. Le Guin. Which if I remember correctly uses name based magic. I think I remember there being a language aspect to it too, draconic being the language closest to the truth of the world and therefore the knowing the name in draconic would be most powerful?

The way I see this affecting spellcasting is the need to learn the true names of effects, elements, and components that make up a spell. Which brings to mind the word-caster system of magic where magic is cast free form by stringing together words of power that determine what the spell does. I think that was from pathfinder’s ultimate magic.

As mentioned by others, how do players interact with this system without breaking everything?

What if true names are not so much given, as they are discovered? Maybe bestowed by the divine entity that blesses one’s coming of age ceremony? And all names used in regular conversation are just nicknames given by ones parents. Does your true names grant you power dependent on their meaning or if historical figures had the same name?

Did you look at 3.5’s truenamer class? Never played it, heard it had a few issues.