I was trying to start carts for Picotron in my RetroPie installation on a Raspberry Pi5.
I eventually figured out how to configure EmulationStation for Picotron and that I can start a cartridge in headless mode by using picotron -x %ROM%.
When I start a game this way from EmulationStation, the screen goes black showing only a blinking cursor in the upper left corner. But I can hear the sound from the cartridge, this means Picotron must be running the cartridge in the background or something like that.
I also tested this on my laptop with Linux Mint starting the linux version of picotron from the terminal with -x and I have the same result: no display, only the cart sound in the background.
I use Picotron V0.2.0h3

Headless mode means no graphics. It's often used for things like servers or backend stuff where it would be silly to do the computations for graphics.

*Edit: So don't use headless mode if you want graphics.

I see (I was hoping headless just means something like fullscreen, but it seems more like something without display output or remote desktop via VNC).