MakeCode isn't just for Circuit Playground Express, it can program a variety of boards, including Metro M0 Express, Trinket M0, Feather M0 Express, and Gemma M0 by using this URL: maker.makecode.com
Click on the Metro M0 Express board on that page, and then click on the New Project button. (If you're new to MakeCode in general, this guide is an excellent place to get started!)
This is the program I built to control neon LED strips. This allows us to use the two buttons to control the sign -- turn the red button on and all of the tubes are lit. Click the yellow button and the two tubes on pins D11 and D10 will alternate blinking every second.
If you'd like to open this program in your browser, click the button above. Then, you can press Download in MakeCode to save the .uf2 file to your computer.
Plug in your Metro M0, press the Reset button to enter bootloader mode, and then drag the .uf2 file onto the METROBOOT drive.
The M0 Express will restart and your program is running!
We'll do a more complete test on the next page as we connect the neon LED strips, but for now you can test the program by clicking the buttons as shown here.