What is “safe app”? Too generic to be googleable.
https://play.google.com/store/apps/details?id=com.kaiserapps...
I stuck to a one-off payment, rather than the garbage subscription models all the other parenting apps use.
It also generates an updated dashboard page from new stuff from all the creators, also essential.
The offline thing has never come up for us. They do a yearly sub $29.99, happy to pay. Just an FYI.
As for the search you mentioned, that might come into it for an older range, for my little ones they still can't read or spell yet, they just want to click on the thumbnail that looks the most engaging at any random time.