Well i have an idea of what could be this power of big mom can be......
When we saw the BM very first time she consumed her own crewmates and pudding was like no problem its everyday story type in mood and in the recent chapter we saw BM saying that "strawberry jam will be made out of blood", thats what i think her power is. She needs to consume other living beings to create new living things. This explains why she is so cruel to eat own crew members or why every non living things is alive around her. This could even explain how a non living beings can ate Devil fruit like in alabasta arc we saw the cannon in baroque works who has dog-dog fruit powers....
When we saw the BM very first time she consumed her own crewmates and pudding was like no problem its everyday story type in mood and in the recent chapter we saw BM saying that "strawberry jam will be made out of blood", thats what i think her power is. She needs to consume other living beings to create new living things. This explains why she is so cruel to eat own crew members or why every non living things is alive around her. This could even explain how a non living beings can ate Devil fruit like in alabasta arc we saw the cannon in baroque works who has dog-dog fruit powers....