Scriptural evidence for the role and compatibility of polytheism within Buddhism? First of all, I would like to clarify that I am extremely new to Buddhism, Hinduism and Indian philosophy in general. I do not particularly consider myself an adherent of any of these traditions. I am doing research on Buddhism as part of a project I have to study the scriptures of every religion.
With that out of the way, I would like to ask practicing Buddhists here if polytheism is compatible with Buddhist doctrine or dharma, and what the role of said polytheistic traditions are within Buddhism. I am a European polytheist who worships many members of the European pantheons, such as Germanic, Celtic, Roman and Greek deities. Is the worship of multiple Gods discouraged or encouraged within Buddhism?
I know that the Buddhist scriptures mention Hindu deities like Mahakala and Hayagriva, but I have no idea where they are mentioned within the scriptural canon, and I have no idea what is said about them or in what context they are referred to.
In summary:

Is polytheism dharmic or adharmic?
If it is dharmic, what is its role within Buddhism?
If it is adharmic, why is this the case?
What is the scriptural basis for your answer?
Is polytheism dharmic or adharmic? Dhammic
If it is dharmic, what is its role within Buddhism? Different level of consciousness leads to different rebirth.
If it is adharmic, why is this the case? NA
What is the scriptural basis for your answer? There are many suttas with the Buddha encountering Deva (Gods) in Samyutta Nikaya, such as in the Devata Samyutta and the Brahma Samyutta etc.
Also refer to the popular blog about the 31 planes of existence.