pip install miflashmiflashScans for .tgz ROMs (current directory, or shared storage on Termux), lets you pick one, extracts it if needed, lets you pick a flash script, waits for your device in fastboot mode, then flashes it. fastboot itself is handled automatically, nothing to install by hand.
To scan a specific folder:
miflash /path/to/romsOn Termux(without root) you'll need the Termux:API app.