“Lord Vishnu and Lord Shiva (in Hinduism) are Devas.”
Ironic that worshipping devas won’t cause salvation.
“I am also not familiar with Buddha Amitabha. If it is a past Buddha (who has passed away), he would not be in any realm of the world.”
Well, not in the realm of Mahayana. Amitabha is expected to “save” you by taking you to the Pure Land if you have faith in him. Many Pure Land followers are convinced that it is not possible to purify the mind by using one’s own efforts so they chant different Buddha names hoping to be born in the Pure Land and be enlightened there.