Hi
Sikhism is not 'Pantheistic', but 'Panentheistic' (as SunnyBacon pointed out), the Sikh scriptures attribute a dual-nature to Ik Oankar:
Akaal-Purakh is "Nirgun" (without attributes/non-physical/unseen) and "Sargun" (with attributes) at the same time. On the surface this looks contradictory, but not when you consider that Akaal-Purakh is the cumulation of the manifest Universe AND the Cosmic laws which govern it, not just one or the other.
The Nirgun (Cosmic law) aspect of Akaal-Purakh is said to have always existed and will always exist. Sargun (manifest Universe) has not always existed in its present form and came into existance as a result of Nirgun.
So whenever Guru Granth Sahib says something like "One Universal Creator God", it simply means that the supreme (natural) Cosmic law, sometime in the past, gave rise to the physical Universe we are a part of today.
In this sense, there is nothing 'divine' or 'supernatural' about the concept of 'God' in Sikhism, it differs from 'Pantheism' because a Pantheist may believe that we are all equally God, whereasthe Guru Granth Sahib maintains that while Ik Oankar is within us all, none of us are actually God, Ik Oankar is distinct: "You established all the worlds from within Yourself, and extended them outward. You are All-pervading amongst all, and yet You Yourself remain detached".
"Gurdwara" means "Gateway to the Guru", "Guru" means "eliminater of darkness/bestower of knowledge" and "Sikh" means "student/learner/disciple". Gurdwaras are not "places of worship" (although they do get called that in the west because the Dharmic philosophies have been lumped together with the Abrahamic religions), Gurdwaras are actually schools where Sikhs go (or were intended to go) to learn more about the philosophy of Guru Granth Sahib.
There is no concept of 'worship' in Sikhi, the Guru Granth Sahib is a composition of poetry which was meant to be sung and played with musical instruments, so Sikhs listen to the music of the Guru Granth Sahib in Gurdwaras, we don't actually 'pray'
The Guru Granth Sahib routinely uses musical metaphors when describing the Universe, that an unstruck melody resonates across the entire cosmos and also vibrates within every fiber of creation, that "celestial instruments" make it so that the Universe is essentially one big orchestra playing in symphony.
So no surprise that music is at the heart of Sikhism
I hope that helped a bit