Then again I actually have no idea.
At first glance, I don't suspect OP is trying to create the best Todo application of all time.
"I built to learn about progressive webapps or PWA"
EDIT: Thanks for the explanations!
It's essentially a sample app for the offline-first approach to application design.
I don't exactly get why this is posted here. It seems like OP did this for the sake of his own learning, and that's well and good. But this is not a particularly interesting project and doesn't do anything novel.
The OP isn't claiming to have done more than gluing together a bunch of stuff. And I don't think I can install a shell script on my phone. And it won't have equivalent functionality.
There're too many over engineering that call itself "simple" .