Checkbox settings and colour configuration

Np. You need to call updateItem() outside of onMenu() somehow. onMenu() is only called when the user presses the menu button.

For example, you could call updateItem() in onSettingsChanged(). Similarly, if your menu labels/contents change somehow based on user input, you can call updateItem() in the menu input delegate.

So what you are trying to do is update a menu on the device, while it's showing, by changing app settings from a phone.  Is that correct?

Yes, that's exactly correct.  The user should be able to compile their own list on the phone settings menu by choosing a label and items under each list (like a to-do list which can then be crossed out when they are done with it).

Right, so when updateSettings() is called, you would have to run your own code which add, deletes, and updates menu items as necessary. (For the best possible user experience.)

Regarding changing the appearance/color of the menu, you would have to use CustomMenu and CustomMenuItem, I think, which means that you would have to render your own menu items and forgo the CheckboxMenuItem class that you wanted to use. (This does mean you would lose the device-specific appearance of checkboxes.)

The easier way to do it might be to have a static menu which is programmatically popped and recreated when settings change, but that might be visually jarring.

You may find it's easier to just not use a menu.  What it sounds like you have is a list, where the user selects something and then acts on it.  Here's one of my apps, where I build the list based on a makeWebRequest, then using up/down (or swipes) highlights an item, and when the user selects an item, it displays info for that item (no reason that part couldn't be a menu). or that the main list isn't generated with onSettingsChanged.

Another option I use is to have a screen per item.  Here's another app where I scan for BLE devices, and the number can grow (again, could be based on onSettingsChanged.

The "Result 9/9" indicates I'm on the 9th item out of 9, where again, up/down cycles through, and select displays aditional info.

Neither of these was complex to do, and allows you to use whatever colors/decorations you want, and you aren't limited to devices with Menu2.

Those are great suggestions.

Or if you still want something that "looks" like a Menu on old devices, you can use DMenu for CIQ < 3 and Menu2 for CIQ 3. (To be fair, the UX isn't perfect.)

In the case of the WU forecast app, using menus of any sort take up too much if the screen.  This way I can show all 5 days on a single screen and dig deeper if needed.  For the blescan, each item has too much to display using a menu and can easily show more data using select.

Depending on the app, a menu can just get in the way. And in this case, not using a menu can simplify things when it comes to app settings, colors/decorations, support of more devices, etc

Yes, I want to create custom todo lists that users configure to their needs, which a user taps or swipes through then cross on or off where needed.  I first attempted to set up the lists in the form of an array in which the units are rearranged based on the user action giving the illusion of scrolling up/down, but I've found CIQ to be very limited in that aspect when it comes to arrays so that did not work out.

Your first image looks similar to the functionality I want (but the Menu2 checkbox looks nicer!).  Still trying to decide the best way forward.