1Blocker consists of:
- Safari Content Blockers
- Safari Extension for additional blocking with JS
- Local VPN for blocking ads/trackers etc. in apps (on iOS)
The last one you might not be able to use if you're also running NordVPN on the same iOS device. However, if you run NordVPN on your router or something like that, then you can use them at the same time. The Safari content blocker and extension you can always use even when you use another VPN on the same device.