I was able to make a version for Ubuntu (64bit)! Install it via the Itch App or grab it from the Pixel Fireplace Downloads page.

The only small issue I've found is Pixel Fireplace can't prevent Ubuntu's sleep settings, so you'll have to adjust them if you don't want the display/computer to sleep while it's running passively. Everything else seems to work fine including dual screen support, but let me know if you find something. Some more details from the GM:S website:

"Ubuntu 16 or later is required. Other distros can usually run the games that GMS2 generates with no issues, but we only state support for Ubuntu, so if you have issues playing games on these other platforms you will need to investigate this yourself. All games are 64bit-only"