Alternatively, you can build an Adafruit MacroPad in 15 minutes. It's the same concept with a custom keyboard, an OLED, and a rotary encoder. I've been using it for years, and not only is it compatible with Linux, but the code is also available and is 100% customizable.

Site is hugged to death, but looks like the XPPen ACK05 product mentioned in title is a Bluetooth shortcut pad that looks like a number pad with an iPod wheel, intended for artists to quickly undo/redo, switch tools, and zoom/rotate canvas.

Titles are hard but something like "The XpPen ACK05 remote on Linux using only FLOSS" would be less wordy

For those who don't RTFA and just see the headline: "Floss" as in FLOSS (Free Libre Open Source Software), not Floss as in the teeth-cleaning instrument.