My oldest (12) likes to draw, and is currently using a free version of ibisPaint on her phone.

What's a good upgrade to that?

I'd love to get her a tablet + pencil, but I'm not quite ready to shove an overpriced Apple thing in her hands. But I also want to encourage her and not give her crappy tools/software.

@pixelambacht Maybe @davidrevoy has some suggestions?
@jelte @pixelambacht Yes, she probably already knows what she wants, and it could be an Apple. The real strategy here is to preserve her passion for drawing regardless of any software or hardware considerations. She may change her mind when she experiences problems herself later on. Ask her about upgrades she's seen in her community, both hardware and software. Sit with her, write down her dreams, compromises, and study them together. Involve her in this hardware quest. :)
@jelte @pixelambacht But for a more practical advice: a laptop found on the second hand market and compatible with a KDE Linux distro (like a performant Thinkpad) and a graphic tablet like a Wacom connected to it (it can be a screen, or screenless tablet; small models are not that expensive nowadays). With Krita (appimage package). A powerful studio, full of possibilities (drawing session can be recorded with OBS, video cut with Kdenlive, etc).
@davidrevoy @jelte Thanks! That might be a solution too. There's a laptop they've been (under)using so who knows what that brings.