Thanks. Great tip for iPads but probably doesn't work with Kindle devices.

Bought for partner and their Kindle. Recommend. https://www.amazon.com/dp/B08T8CZYF3

(no affiliation)

Fascinating! Any idea how do these work?

Simulates capacitive touch.

https://patents.google.com/patent/US10310677B2/en

For Kindle, there are wireless page-turner attachments. Supposedly you can use a Bluetooth dongle to connect to a standard Android remote clicker, after jailbreaking. Jailbreaking my Kindle was a very frustrating project, so I gave up on that in favor of using an android device, so I could read lying on my back as you described.