Brian,
Don't forget that one quick and useful way to activate or open a palette is to drag and drop it from the Studio Palette window into the current project's palettes.
This will create a new page/tab in the palette window.
We don't have to be precise here when opening as we can drag and drop a palette right onto the canvas area as well.
One of the easiest ways to open a palette is to use OT's browser window to locate a palette and then drag and drop that into OT.
We can also select multiple palettes at the same time and when we drop them into the current pallet (or OT) all of them will be added as new pages of the palette.
In short, OpenToonz will recognize the palette's file extension and know what to do with it.
Saving can work much the same way.*via drag and drop" but it can take a little experimenting to get a feel for what to grab and where to drop.
The palettes need to be dropped onto a folder.OR INTERESTINGLY a sub-folder in the Stuidio Palette window.
I need to explore OpenToonz palettes myself because there is a lot going on there that I'm surely unaware of.
The bottom line here is that if we know where our palettes are (outside of OT or within the Studio Palette window) it's easy to access them via drag and drop.