Sounds like you just want to write GCode? There are some helpers to make it a little less tedious, like FullControllGcode. Gcode, especially for printers, is really 2 commands, G0 and G1, so writing your own helper is also pretty easy.
There is a lot more to it than that. For instance, for overhangs and bridges you need fairly fine control of the fan in relationship to the movement of the extruder head. You'll need to do circular interpolation in such a way that the toolhead does not slow down too much or you'll get really crappy corners and seams and other joints can be really hard to do properly if you are just using naive point-to-point moves rather than lots of little tweaks to get partial overlap between the two adjacent paths. And then there is control of the extruder retraction and pressure advance, which are pretty complex and difficult to get right for even a subset of the most common use cases, especially if you want to have a range of speed options. "pretty easy" does not match my experience so far, but then again, I am only using this when the regular slicer can't cope so there is a chance that the problem is me.
I want to _generate_ gcode (using a high-level language), then run it through a simulator which can show me what the results will look like (for a given tool head).
For me, it would be nim. A single language that can run on all sidesof the stack, great to write in and ~fast compile times. It helps that I have been toying with it for years, but it's definitely the language I enjoy the most.
Of course the ecosystem is not huge, so you have to roll your own solution a lot, although it's getting slowly better.
Jester+custom HTML dsl+compiling nim to js makes for a good experience, imho
