Hey John,
OnefinityCNC frequently stated they will never support VFDs/spindles
Onefinity recommends the Makita hand trim router but I can’t recommend it since it is not allowed for use in a stationary machine (is a warning in the manual and it is confirmed that you loose warranty in the same moment you mount it into a CNC) and it is likely to burn your workshop down.
Unfortunately there is still no 43 mm mount available for the Onefinity so you don’t have the chance to use a professional, CNC-approved milling motor like AMB (former Kress), Suhner, Mafell which are plug-and-play and require no VFD. So the only alternative to the Makita hand trim router on the Onefinity is a spindle with VFD. If you manage to install one, it is the superior motor, induction motors are the workhorse of the industry and their efficiency is excellent, and you have a constant torque from 6,000 to 24,000 rpm (while with the Makita trim router, when you have torque, you have no speed, and when you have speed, you have no torque). High torque at high speed is what you need when milling wood.