My dad recently had a stroke and was in a coma. His current situation is he is not coherent. I need his personal belongings, phone, wallet etc in order to act on his behalf for his business and my younger sister. How can I get the hospital to give me his belongings without having POA/guardianship?
Have you talked this over with the hospital social worker?
I can understand that a hospital would not be eager to give away a patient's belongings to just anyone. You are not just anyone ... you are a close relative. Ask what you will have to do to get the belongings.
If your father does not fully recover from being incoherent, you (or someone) will probably need guardianship. Perhaps you should start looking into that.
(I assume your mother is not in the picture, and that he does not have a wife. Is that true?)