> There is a proposal in TC39 for native signals,

Which originated (or the modern versions of signals originated) in Solid, not in Lit.

Let me quote the readme: https://github.com/tc39/proposal-signals

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The current draft is based on design input from the authors/maintainers of Angular, Bubble, Ember, FAST, MobX, Preact, Qwik, RxJS, Solid, Starbeam, Svelte, Vue, Wiz, and more…

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