Here are the words exactly from the Greek.
"This moreover is eternal life that they should know you the only true God and whom you have sent Jesus Christ".
It couldn’t be more plain than that.
Re “and Jesus Christ,” (Jn. 17:3) the word “kahee” (and) sometimes has “a cumulative force; as in “also, even, so, then,...” (Strong’s)
This cumulative sense makes sense, for rather than teaching eternal life is to know two separate beings, Deity and non-deity, instead, and consistent with John, it is teaching that eternal life is to know the one true God by knowing Jesus Christ, God manifest in the flesh, (Jn. 1:1,14) thus “Whosoever denieth the Son, the same hath not the Father,” (1 John 2:23) and “He that believeth on me, believeth not on me, but on him that sent me. And he that seeth me seeth him that sent me. (John 12:44-45)
And note that the above verse is in the context of the Lord Jesus being the one whom Isaiah saw in His glory in Is. 6, when he saw the Lord sitting upon a throne, high and lifted up, and his train filled the temple..., at which time was given the prophecy so often quoted in the NT,
And he said, Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not. Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and convert, and be healed. (Isa 6:9-10)
And we know that the Son of God is come, and hath given us an understanding, that we may know him that is true, and we are in him that is true, even in his Son Jesus Christ. This is the true God, and eternal life. (1 John 5:20)