I'd grab any USB stick and boot Linux from there...or if you'd like to try out a bunch from a single USB try Ventoy
https://www.ventoy.net/en/index.html
And of course there's Tails if you'd like to use a USB as your main OS:
No need (really) to install Linux native, but if you find a distro you like, then installing that makes sense. But for now, I'd just have her boot directly from a USB...