<p>I am searching for a Linux software to control the 3000 mW laser engraver depicted below. It's a common model you'd find on AliExpress, Banggood, etc. under different brand names.</p>

<p>I have already tried <a href="https://github.com/AxelTB/nejePrint" rel="noreferrer">nejePrint</a>, <a href="https://github.com/LaserWeb/LaserWeb4/wiki" rel="noreferrer">LaserWeb</a>, and <a href="https://github.com/camrein/EzGraver" rel="noreferrer">EzGraver</a>, but they don't work. Any ideas?</p>

<p><a href="https://i.stack.imgur.com/kHoYY.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/kHoYY.jpg" alt="enter image description here"></a></p>

A program that lists as functional with Linux is
Lightburn
. It's new to the laser engraving world and supports GRBL type controllers as well as Ruida brand and possibly a few others. If you can determine your controller, you're a step ahead of the game.
Directly from their site:
LightBurn
LightBurn is layout, editing, and control software for your laser
  cutter. With LightBurn you can:
Import artwork in a variety of common vector graphic and image formats (including AI, PDF, SVG, DXF, PLT, PNG, JPG, GIF, BMP)
Arrange, edit, and even create new vector shapes within the editor, with powerful features like offsetting, boolean operations, welding,
  and node editing
Apply settings like power, speed, number of passes, cut order, brightness & contrast, dithering mode, and much more
Send the result directly to your laser cutter
LightBurn is a native application written for Windows, Mac OS, and
  Linux.
I'm a satisfied Lightburn user, not a company representative.