As mentioned below, the main problem is the detector. Most detectors are Si CCD. meaning the Si is fundamentally limited to 1100nm due to bandgap. Going beyond that means you need a different material such as InGaAs or Ge, unfortunately CCDs are not as common or are expensive for these materials. Which then gives you two choices:

- an array detector, which is pricey.

- a single detector such as a photodiode behind a second slit. a detector such as these https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=12... With a moving(rotating) grating, so that the wavelengths can be reached by moving the grating.

The latter is quite common in lab spectrometers.