@JKSH: yes, I think you're right. The page on configuring for bare-metal devices is a little unclear, but it does say this:

However, if the device does not have Qt libraries, you need a fake Qt installation.

Not sure what a "fake Qt installation is," though, and the page doesn't elaborate on this.

Currently, when I try to use one of my non-fake Qt installations, I predictably get this error:

warning: "C:\Qt\Tools\mingw530_32\bin\gcc.exe" is used by qmake, but "C:\msys32\opt\xtensa-esp32-elf\bin\xtensa-esp32-elf-gcc.exe" is configured in the kit.
Please update your kit or choose a mkspec for qmake that matches your target environment better.

I'm not sure how to proceed from here...I could create a mkspec for the cross compiler, but that doesn't solve the problem of what to use for a "fake Qt."

I just noticed: In this screenshot, your esp32 kit does not have a Qt version set. That could be why it doesn't appear in your list of selectable kits.

If you have set a valid Qt version but still can't apply the kit to your project, try creating a brand new project (Qt Console Application): Is the kit selectable then? What about a Qt Widgets Application?

That's exactly what I've tried to do, a few times. The new kit just doesn't show up.

My kit is now displayed without errors (and with a device) but it is still not showing up in Build mode. Do I need to add a line to my .pro file to enable the visibility of my kit?

No, .pro files know nothing about kits.

1. Open your project in Qt Creator
2. Click "Projects" in the Mode Selector (the upper-left bar)
3. Under "Build & Run", click on your new kit to activate it for this project
4. Click the Kit Selector (the "Debug"/"Release" button on the lower-left) to select your new kit
5. Click "Run" button to build and run your project, using your new kit

See the top screenshot at http://doc.qt.io/qtcreator/creator-quick-tour.html for the Mode Selector and Kit Selector.

I'm trying to follow the directions on the page you linked, but my device still doesn't show up. Also, step 4 mentions:

Select Tools > Options > Devices > Add > Bare Metal Device > Start Wizard:
In the GDB server provider field, select a GDB server or hardware debugger.
Select Apply to add the device.

I see no such "Start Wizard" command.

EDIT:

Oh - is this plugin valid for Linux only?

EDIT II:

OK, I found it. I'd probably word the instructions a little differently:

Tools > Options > Devices > Add

should be:

Tools > Options > Devices > Devices > Add...

That'll make it a little easier for boneheads like me to find when we're rushing...

You should maybe asked the folks on the Qt Creator mailing list.

The esp32 runs FreeRTOS -- is a bare metal option the best way to go for this?

Can you post a screenshot of your preferences ?