Build an Android UHF RFID app (written in C#) using Java/Kotlin

MAGICBOX PROJECT
We're looking for an Android developer to build a version of our current UHF RFID application (written in C#) in Android using Java/Kotlin.
Our current product is an RFID powered smart-fridge system.
This project involves Conversion of an existing Windows C# RFID system to Android application, calling on Native serial RS232 ports on industrial Android board.

1. HARDWARE INTEGRATION
 2 x UHF RFID Readers (RS232)
 Payment Card Terminal (2 models) (RS232)
 Door Lock (RS232)
 Thermal Probe (RS232)
 QR Scanner (RS232)
 Integration of 3rd party E-wallet system (REST API)
2. SOFTWARE BUSINESS LOGIC
TRANSACTION
1. Reader records Inventory of Tags in cache (CurrentInventory)
2. System waits for Customer to Tap Card/Scan QR
3. System sends signal to Unlock Door, Start Transaction
4. System waits for Customer to Review Transaction, Scan Inventory of Tags (NewInventory)
5. Calculate (CurrentInventory)-(NewInventory) to display
RESTOCK
1. Allow Restocker to log in
2. Display total tags inside system
3. MACHINE SETTINGS PAGE
Device Settings + Test
4. LOGGING REQUIREMENTS
Slack Alerts
Logging to SD card: Device Level + Software events level
5. CLOUD MANAGEMENT SYSTEM INTEGRATION
Link to existing Cloud Management system using REST API to sync the following:
 Realtime Transactions
 Error updates
 Inventory Updates