Currently Unreal Engine (4.22) doesn’t have any support for niagara systems on mobile devices and doesn’t appear to be on the roadmap for future versions. mobile support will be good for mobile app development as well as development for standalone VR devices such as the Oculus Quest
Niagara is a VFX tool that is platform agnostic and is meant to be a replacement for Cascade (eventually) and will have support for Mobile devices. I’ve not tried launching onto a device at the moment because I’m not set up for it on my current workstation, but if you use the Mobile Preview in the Editor, you can see that the default Niagara Systems are working. However, just like Cascade, there may be limitations to what types of emitters and systems you can run on mobile devices.