There is no orthologous method for ECDSA that you'd use to directly encrypt data to a recipient key as you would with RSA. ECDSA is purely for signing.
Well I have no idea what orthologous means in relation to cryptography and appears Google doesn't either, lol. I know EC cryptography can be used for asymmetric encryption, but it probably wouldn't be a great idea, which is why I made that edit mentioning the shared secret can be used as an encryption key for a strong symmetric encryption algorithm.
What you're describing (using the shared secret for a symmetric cipher) is known widely as Elliptic curve DiffieHellman (ECDH).
I'm aware of that, the whole reddit post I just quoted describes how ECDH works. And actually ECDH is just a way to agree upon a shared secret, not an encryption technique. The main point I was making is that we don't need to use the shared secret as the value we use to increment Q, we can actually use it as the key for a symmetric cipher which we use to encrypt a second shared secret, which is the random value we use to increment Q.