Any Tablet with an external Hardware can make a nice Instrument. The professional part lies in that external hardware and usability of the software or app. Windows Virtual Instrumentation are well known. Things like USB Scope and Data Loggers have been there for decades.
Now we have Android in which an Open Source product can be developed. The Open Source is both in Hardware and Software.
See a android virtual instrument - OsciPrime is an Open Source Android high speed data acquisition hardware platform and Android oscilloscope application.
Open Source Android Oscilloscope
Virtual Instruments for Android has a nice future in Industrial, Automotive and Measurement areas. You could start by Interfacing with Bluetooth, USB and then move to IoT and WSN.
Android OPC UA SCADA and Client
TeslaSCADA is a SCADA for accessing production and process data through smart phones and other Android devices, using the industrial communication standard – OPC Unified Architecture (UA).
These were some questions i got a few years back...
1 - If i had to create a crude "Lux Meter" and "db Meter" using the built-in camera and microphone on a Android Device - How would i Calibrate it ?
2 - Is there a Component(software) for Android to interlace with a Arduino Device as an external interface, This will help us make a DMM/Scope or even a Entire Lab Test bench centered around a Tablet and a Plug-in Mini Instrument Rack.
Both Sound or db Meters and Lux or Light Level Meters are in the Google Play nut need calibration. All These Instrument Needs a USB/Bluetooth Sensors.
Add Bluetooth you can carry your Tablet away from the instrument probing the DUT. (Device under Test)