ChaCha20-Poly1305
The other modern AEAD. A stream cipher plus a tag. First-class in TLS 1.3, especially where AES hardware is missing.
ChaCha20-Poly1305 is an authenticated-encryption construction: ChaCha20 is a stream cipher, Poly1305 is a one-time authenticator. IETF RFC 8439 specifies how they are combined. Like AES-GCM, you get confidentiality and an integrity tag. Unlike AES, it is not a block cipher, and it is fast in software when there is no AES-NI.
TLS 1.3 lists it as a first-class AEAD cipher suite next to AES-GCM. Mobile, IoT, and older CPUs often prefer it. The operational rules are the same as any AEAD: unique nonces under a key, a current library, no home-rolled variants.
This is not a reason to run both for the same session. The stack negotiates one AEAD. Pick current TLS and let the implementations choose. Do not invent a hybrid of AES and ChaCha because a slide said defence in depth.
Fact source: IETF RFC 8439, ChaCha20-Poly1305.