Biggest problem is app embedded web views don’t count as Safari, so if you try to block the web on a mobile, you have to block or time restrict every default app that has the remote possibility to open a link to a web view. Looking at you, Stocks…
Only to realize there’s a built in browser that you can bring up if the book embeds a link.
It’s a safari browser but under the rules of the Libby app.
Settings on Apple and then separate profile with nextdns too