There are several levels, there are countless variations within those:
- Hot-swappable cells that won’t explode if you put in a battery the wrong way around like this, I have not seen any that do pd though so they are not that useful here.
- Cold swappable cells that need to be matched and will absolutely blow up if you put in the battery the wrong way around like this as a quick example, those come in all shapes and sizes and from one 5v 500ma to multiple 100w PD outputs.
- Boards where you have to wire your battery pack to yourself, with and without integrated bms like this.
The hard part isn’t finding them but separating the good ones from the bad ones.