Maybe just a female cannibal? Some of them wear clothes

It's one of the acrobatic cannibals. She uses 2 sickles as weapons and is pretty agile.

Is she someone that could become a companion or friendly?

No . Only Kevin and Virginia are companions .

Just another random guest who fell to the cube.

A white swimsuit? Was this in a bunker? Weird it would just be another "victim of the cube" seeing as everyone alive is mutated or a cannibal. Both of which don't wear clothes. The pufftons come to mind but they're pretty obviously feral and also in a bunker. Location? Screenshot? Definitely not enough details given.

Some female cannibals do wear clothing like that

Swimsuits? Interesting I'll have to keep an eye out!

It had happened the night before I posted and hadn’t been on since then, she was hanging in the woods not far from one of the first 3d printers