Brushless drone motors suffer from too high a kV (~operating RPM), needing a lot of gear reduction for this kind of application, but I take your point about volume.
Gimbal motors (also in drones) are closer to what is needed, and often come with encoders and centre pass through holes for cables.
Some manufacturers now make larger versions [1] with gearing and a built in motor controller, originally more for robot dogs than robot arms so backlash etc is worse, but the low gear ratio lends itself to cobot type.
For more conventional robot arms (high precision and stiffness) the harmonic drive gearbox patents have expired so there are some [2] of those coming out of china. This offers a really high reduction and very low backlash.
Gimbal motors (also in drones) are closer to what is needed, and often come with encoders and centre pass through holes for cables.
Some manufacturers now make larger versions [1] with gearing and a built in motor controller, originally more for robot dogs than robot arms so backlash etc is worse, but the low gear ratio lends itself to cobot type.
For more conventional robot arms (high precision and stiffness) the harmonic drive gearbox patents have expired so there are some [2] of those coming out of china. This offers a really high reduction and very low backlash.
[1] https://www.myactuator.com/product-page/rmd-x8-pro
[2] https://www.myactuator.com/rh-14details