Comment by mkl
The ō is an o with a macron. It's pretty easy to install a keyboard layout that supports it: https://kupu.maori.nz/about/macrons-keyboard-setup. Many mobile keyboards support it by default with long presses to pop up an accent/variant chooser.
> It's pretty easy to install a keyboard layout that supports it
Only if you don't need anything else from your keyboard layout. I use Dvorak and need to type Japanese, and I think either of those makes it impossible to enter macrons on Windows.