Boppy pillow warning ?

My 7 week old son hates sleeping on the firm/hard mattresses. He wakes up and refuses to fall asleep. It's been like this since day one. He also hates laying flat due to reflux (he's on Zantac from the Dr). . So to help him we put him in the boppy since week one. . Now I'm reading how babies are dying after falling asleep in the boppy. I'm scared to let him sleep in it now. But laying on the firm mattress is actively making him mad as I type this. . We don't have a crib yet. We have the pack n play. Or a bassinet. He hates both. The boppy was the first thing he would fall asleep in . Suggestions?? or do you think the boppy is ok? Idk what to do.