There is a company called Kaiser optical which makes some handheld Raman units. Renishaw may have some options. I do not think Jobin Yvon does any supercompact stuff, at least they didn't last time I was there. They wanted to charge me thousands for a fiber head for my system. After I already paid $200k for the monochromator. I do admit that it is a Rolls Royce monochromator, but still...
Generally the best option balancing resolution and size is to get a larger single monochromator (460mm or so) for better resolution, and then get a probe head fitted to that. Altogether it shouldn't be hard to get a suitcase-sized system that gives you very good resolution.
If you try to build one yourself, the main cost will be the notch filter, which you need to filter out the excitation light. But I am sure that on a site like labx you can find used stuff going for peanuts.
I can easily imagine a pen-sized laser pointer/Raman system, but.... ultimately the spectral resolution is going to be proportional to the size of the thing. I mean, if the actual monochromator is handheld then you are going to get crap resolution unless you fold the beam very cleverly.