I haven’t used their new iOS app, but it’s a welcome addition. In the past you had to sync your Zotero library with another app for PDF annotation that was synced (papership). It was never something I’d call robust or seamless and the papership app has felt like abandonware.
I’m looking forward to trying the new app today.
The Apple Pencil support is still pretty rough, but it's been getting better every update version. I've been using it for the last couple of months.
The iOS app doesn’t come up as the first result in the App Store. Not sure if it’s because Zotero isn’t popular enough yet.