Bootcamp Boot Disk Selector Can't See the Mac Volume

I set up a 2010 Mac mini as a headless Mac connected to a TV. So I guess not really headless, but keyboardless. It's in my bedroom, with a Playstation controller plugged in. I do all the typing and clicking over VNC using my laptop.

So I installed High Sierra on an APFS volume. Then I used bootcamp to install Windows 7 on it's own volume. Then I installed all of the bootcamp tools into windows.

Everything works great, I can play the old GTA games I like on the windows side, I can use OpenEMU, youtube or whatever else on the Mac side.

BUT ALAS, there is one big problem. I can't boot into macOS! This is because my only keyboard control is via VNC, so I have no way to hold the option key at startup. And for whatever reason, the startup disk control panel IN WINDOWS cannot see my Mac volume. This is the proper solution, just go into that control panels, select the High Sierra volume and reboot. But it can't see it. Is there some way to fix this so it does see it?