I mainly use termux for the script API (which is incredible btw). I usually write the scripts in bash or ruby on my computer and scp them over, but I also have a small keyboard that I can plug in to type directly on the phone.

Even if you don't use the CLI part of Termux often, it's still an incredibly neat piece of hackery goodness. I once needed to text about 50 people and have it be from my real phone number. Rather than hack around with Twilio or AWS, I spent 5 minutes writing a ruby script to send the texts from Termux. If you aren't familiar yet with the API, it will take a little longer than 5 mins the first time. Once I had that script, I kept finding neat usecases for it. I sometimes still just text from the CLI because it's easier than using the built-in messages app depending on what I'm doing.

You can definitely get an amazing experience on Android without Termux, but Termux is like if Android were a really nice bicycle, Termux is a small powered motor you can bolt on somewhere to automate parts of your life.

Aside: I find Termux easier to use than Tasker. I'm a CLI native old man though, so don't take this as a knock against Tasker.