deleted on Nostr: If they are there, then they should be available to other apps, but you have to grant ...

If they are there, then they should be available to other apps, but you have to grant those specific apps permission to access them. Normally, you receive a prompt for this when launching the app for the first time. It's also possible you granted access to Contact Scoops, a unique #GrapheneOS security feature that you can read about below. If it was Scoops, by default the app cannot read your contacts. You can add exceptions, though.

https://grapheneos.org/usage#contact-scopes