If you are going to buy a small machine off the shelf so to speak please make sure there are NO 3d printed parts involved. You may have to pay a little extra for such a machine but you will thank me later LOL.
Once you get above a certain size the G-CODE control mechanisms change from mostly GRBL based to MACH based.
However once you have played with a smaller machine moving up to a MACH based machine is quite a short learning curve as you will already have most of the basics down pat.
Better also to avoid those that have the Arduino NANO based control board approach and go for the UNO based.
Currently use my stuff mostly on hardwood so I know if I slow them down even just a small amount they would also be fine for Aluminium.
Don't know what your budget is but a decent size laser of 5W or greater is a fantastic addition and opens up the machine to a lot of new areas.
Don't use Linux here so cannot say much in that aspect.
Bob
This pic might get your juices flowing LOL
