Portable Charger Power Bank for air travel

My daughter will be going to Spain with a group from her school in a few weeks. It was mentioned to her to get a power bank that was TSA approved. She will probably not have access to recharge anything for 48 hours. She has a Pixel 6 and probably an iPad too but not the top priority to keep charged. I wasn’t sure what TSA approved was and what the requirements are and wanted to see what recommendations anyone would have. I’ve never really traveled to don’t know what to look for. Thanks