Flespi MQTT integration iOS(swift)/Android(kotlin)

RejuRS

Can anyone suggest any libraries for Flespi MQTT iOS(swift) and Android(kotlin) integration?

dexif

There are no libraries that implement any specific flespi MQTT functionality.
You can use any library that supports MQTT 3.1.1 or 5.0
For example you can use KMQTT or CocoaMQTT