Is there a way to make Nano support auto-complete and auto-bracket closing?

As of at least Nano 2.9.8, autocompletion is supported.

Pressing ^] (C-]) will check for words beginning with the current prefix in the current buffer and grab the first one. Pressing ^] multiple times will cycle through the available matches. Regardless of how many times ^] is pressed consecutively, ^[u (M-u) will undo all of them as a unit.

I just downloaded and perused the source of Nano with some grepping. I can say with 95% confidence that Nano doesn't support auto-bracket or auto-complete.

Meta-] will jump to the matching bracket under the cursor though.

Sorry!