No. You cannot flash a full operating system from within the OS itself. Any APK claiming to "flash firmware" is a scam. Flashing must be done via a PC.
Here's a general step-by-step guide on how to flash the Nokia G21 using a flash tool: nokia g21 flash tool full
To successfully flash your Nokia G21, you need a collection of four critical components. We call this the . Flashing must be done via a PC
You cannot flash without all three.
: This is a professional service tool frequently cited for performing "Hard Resets" and "FRP Bypasses" on the Nokia G21. You cannot flash without all three
Nokia has started rolling out Android 14 for the G21. If you manually flash using this tool, you will bypass the OTA queue and get the update instantly.
If the drivers are correctly installed, the tool will detect the phone, and the progress bar will turn yellow/green, showing the writing process.