Best hardware setup for children's homes in Kenya

I run a non-profit organization that provides internet connections for children's homes in Kenya, allowing them to receive free weekly yoga classes via Zoom, conducted by a team of volunteers.

Currently, we use donated iPad devices, which, while small, have been quite impactful.

I am now exploring long-term solutions to improve this setup. Here are some options I've considered:

1. Google Chromecast: The issue here is the lack of a native app.
2. Android TV Box: Similar issue with no native app.
3. Raspberry Pi: Concerns about the quality and increasing costs.
4. Cheaper Tablet: Plugging it into a larger screen could work, but the camera quality is poor, so we would need to purchase an additional webcam. Also worried how long will zoom work on a cheap tablet for?
5. Logitech Rally Bar: Excellent quality but far too expensive.

I am open to any suggestions for the best setup. Ideally, it should be cost-effective while providing a reliable experience. I am particularly concerned about the longevity and reliability of solutions like side-loading an Android app onto an Android TV.

Any suggestions would be greatly appreciated!