I would purchase a very cheap Tablet because you can still borrow books from your Library using it. Look at the website Borrowbox.com for more information.
Samsung has a book app offering free books that can be tailored to the reading experience of your Children. All worth checking out. This will save you time and money.

When my daughter is a little older I will be doing this. We have an iPad and will look for book options on this. If I was to choose between the two options you have advised for opinions on, I would go with the kindle as I believe it would offer better options that your other suggestion.

Little cheeky, but we have an iPad and find there are so many books you can download. It’s tricky with kindle, because you don’t own the books. I really don’t love that. Have you heard of the app Libby? I used to when I lived in the Darling Downs region, the public library there encouraged accessing it. You can borrow ebooks, audiobooks and put holds on physical books. Just find your local library in the app, link your card, and see what’s available. I have borrowed amazing Manga and graphic novels this way

Hey, I would 100% go the Amazon Kindle for your 10yr old, they have a kids setting/kids account so they don’t get inappropriate content they are black and white so they look more like paper but you can get a kindle with colour. I have a kindle and absolutely love it you can have up to 20 borrowed books from kindle unlimited then however many you want that you purchase. It’s simple to use so absolutely kid friendly. I also think kindle have more of a selection than Kobo do.

I cant help much on the technology sode but i believe the Kindle is black and white – this may have changed

There are a couple fo apps that may better suit what you are looking for that you could test out on your phone before purchasing a tablet.
– Epic is an age specific library with lots of picture books, read to me and audio books (may suit your 6yo)
-ReadingIQ has picture books with more of a focus on learning
I domt know much about any apps with Magma sorry but worth also checking parental controls on them.