Find a MIDI controller with some knobs and keys. There are some really nice ones for pretty cheap. I like the look of the Native Instruments Komplete Kontrol M32 keyboard for the price.
Upgrade to a really fast computer.
Get a nice Audio interface if you haven’t yet, especially if you’re using your computer’s built-in audio.
I can’t think of any hardware that would really enhance using VCVRack per se. There are reasons one might buy hardware, but that is a personal question of how you want to work, and most importantly, how much money you have.
Eurorack is a money pit. I have a lot of experience with hardware modular synthesizers, and they’re fun and all, but VCVRack gives you that experience with a lot more flexibility.
Remember that what you’re working with is a musical instrument, and practice is the most important component to being fluent and musical with it, even with just a keyboard, mouse and Rack. The more I experiment with putting together performance patches, the closer I get to something musically compelling without adding in thousands of dollars of gear.
And that’s speaking as someone with thousands of dollars of gear.