Except not simple, because apparently you need an apple device to manage "Family Sharing" and you CANNOT do it any other way. They won't let you do it at an Apple store, they won't do it for you via Apple Support... you're just fucked.
My family hasn't had an apple device since my iPod Touch 3rd gen back when I was in high school. Even if I could find it, it's probably jailbroken and too old to manage the subscription anyways.
I hate that this is how apple gets me to buy their devices. (Goddamn these things are expensive second hand)
I have lots of old gear still working and will swap for something interesting. My ex has unknown numbers of hand-me-down iphones, usable with wi-fi.
I mean, a 2010 laptop, an iPad 1, and they still are useful for text editing, photo albums, and the original iPad function, holding music scores and books, saving hundreds of pounds of tree books and printouts. And more. I can't be the only one.
Guy Kawasaki (known to old Apple old-timers) said, and I quote: "Don't kvetch; Kick Butt"