This app alone is one of the huge reasons why I prefer Android. I love that I can natively run a bunch of Linux utilities directly on my phone and use it like I would a regular computer. Everything from Vim, Python, and various networking utilities, I've played around with so many different tools which has helped expand my skillset over the years.
I also use the Termux-X11 addon to have a full xfce desktop environment running on an external monitor with HDMI out over USB-C.
Phones are quite capable devices and using tools like these really unlocks their full potential.
While Termux doesn't require root, my device is rooted which allows for a lot more.
A few examples:
Using mitmproxy to capture and analyze app traffic from phone apps (automated w/ a widget shortcut to configure android proxy settings on launch and then reset back when I'm finished).
SSHing into my servers (mosh is useful to keep connections alive if network cuts out). I have my own homescreen widgets to automatically launch for specific nodes. Also use tmux everywhere to handle multiple sessions.
Scripting my android phone as a USB keyboard input (simulating BadUSB).
I've implemented my own "lost phone rescue" so I have a way to remote into my device if I lose it.
Reading man pages about a command
Git cloning projects to examine source code when I'm feeling curious
Running web servers for sample projects
Managing files on device (sometimes easier with CLI)