What is the ultimate goal of a Sikh? Is there a reference for it like “Gobind Milan Ki eh Teri bariya”? And what does “Gobind Milan” mean and entail?

Respected Brother/Sister
Waheguru ji ka Khalsa, Waheguru ji ki Fateh!

In response to your question, the undersigned wants to say that Guru Granth Sahib teaches a Sikh to become a righteous (ਸਚਿਆਰ) person and become one with Akalpurakh and Shabad Guru, who are embodiment of each other. The goal of becoming a righteous (ਸਚਿਆਰ) person was laid down by the First Guru Person Guru Nanak Sahib, in the first Pauri of Jap Baani itself, when he said:-

ਕਿਵ ਸਚਿਆਰਾ ਹੋਈਐ ਕਿਵ ਕੂੜੈ ਤੁਟੈ ਪਾਲਿ ॥ ਹੁਕਮਿ ਰਜਾਈ ਚਲਣਾ ਨਾਨਕ ਲਿਖਿਆ ਨਾਲਿ ॥੧॥

Once a Sikh achieves the goal of becoming a righteous (ਸਚਿਆਰ) person, by getting rid of vices, he will become one with Akalpurakh and Shabad Guru, he will live a disciplined life and become virtuous (ਗੁਣਾਂ ਵਾਲਾ) and achieve the stage of spiritual equipoise (ਆਤਮਿਕ ਅਡੋਲਤਾ) and spiritual bliss (ਆਤਮਿਕ ਆਨੰਦ). The final goal is to achieve emancipation/salvation in this life itself (ਜੀਵਨ ਮੁਕਤ) since there is no concept of salvation/emancipation, after death in Sikhism.

As understood by the undersigned this is what is ‘Gobind Milan’. By ‘Gobind Milan ki eh teri Baria’ is meant that whatever you have to achieve is to be achieved in this life itself, since Sikhism doesn’t subscribe to the theory of transmigration of soul and has no belief in past or future life.

Hope it helps. If you have any further questions, please do ask. If you find any deficiencies, please point out the same, for improvement in future.

Regards,
Your Brother