I find Panthiesm to be a highly interesting take on the God hypothesis. Though, I find it almost entirely impossible. There have been two experiments done to try and calculate how much energy is in our universe. The first one was done in 1996 by a groupe of cosmologist ( Adam Riess, Brian Schmidt, and Saul Perlmutter) who used the gravitational lensing around galactic clusters to try and figure out how much energy there is. The result was so startling they thought there calculations must have been off but they couldn't find anything worng with their method. So a second experiment was commisioned (WMAPS) which looked at the ancient structure of our universe (the CMB). It too came back with the exact same startling answer. We we account for all the positive and negitive energy in our universe the total sum energy works out to ZERO. There is no energy in our universe.
This to me, seems to make Panthiesm almost entirely impossible. Though, just out of curriosity, have you ever heard of the book Faltland? Theres a Charachter called Pointland who IS his own universe. People can go and visit him but Pointland can't comprehend anything coming from outside of himself so when they try to speak to him Pointland just thinks its coming from himself.