Hey Carrianne,
I don’t think that stronger steppers will bring the Onefinity CNC, which is decidedly sold as hobbyist machine, into the direction of a machine reliable enough to attempt to start a production and a business. And I say this as someone who bought the Onefinity CNC for professional use, but very aware that it’s not in the stock state that you can expect that reliablity. Before thinking of this, I would first replace the whole cabling and these plugs unsuitable for CNCs, and the money you think to spend for bigger steppers would better be saved to replace the ‘step-and-pray’ motors (aka open-loop) by something reliable, not forcibly closed-loop steppers, linear encoders on glass scales are something very reliable too. Also I would make sure there is a reliable cable routing concept with of course strain relief on moving cables (the lack of such there on stock machine is very unserious) and finally, at least for milling wood, add convoluted rubber gaiters to the axes since oiled mechanics like ballscrews are absolutely incompatible with wood dust.
I don’t want to spill water into your wine, you express a lot of joy over your acquisition of this CNC machine that I don’t want to stop you, and I think in matters of hobbyist CNC machines, Onefinity has advantages over competitors. But starting a business requires to really be sure to be able to rely on your equipment. Hobbyists usually have the time to stand beside the machine, but that does not apply to a professional user. I would try to eliminate sources of possible (inevitable?) disappointment before starting a production.
PS: For the 3D model of the machine above, did you measure the machine yourself?