Motor with freewheeling, variable friction and force exertion

You did not mention what min and max speed is required. I suppose you don't want to make any compromise in any parameter ;-)

With stepper and microstepper driver you can achieve better than 0.15 degrees resolution. But what is precision ? Probably wrong because there is motor and microstepping non-linearity and torque is low, dynamic range is low and extra problems come at very low speed.

You can arrange it as dual loop control with load encoder at outer loop. It should improve precision. Let say 13bit load encoder and 32 or 64 microstepping with 400 step motor might satisfy 0.15 precision.

Gearbox helps with torque and resolution but you also need dual loop control and no backlash if you want change direction. There is extra problem if there is a spring in gearbox. If yes then there is a force at output you need high frequency control loop. It might be even impossible to control system when you must consider this force. So expensive gearbox or back to direct drive.

You can substitute stepper with brushless 3 phase motor and encoder with or without gearbox and one or two encoders. Dynamic range and price go up. Torque ??? For high speed you need high bandwidth encoder/decoder. And it's very difficult to debug such a setup in real time as you almost cannot use breakpoints.

Generally when using encoders they must satisfy your precision needs (and not resolution only).

EDIT (as commenting is forbidden): AS5045/8 encoder: I think you need consider mainly non-linearity INL parameters in range of degrees which affects accuracy (worser than 0.15 deg). Also propagation delay in range of 100 us limits speed, 1RPS = 1/4096 = 244us per position tick.

You should be able to measure the current during normal load operation (from experimentation) and then measure the current during an overload (stall) condition, and then use a shunt resistor (like, a 1% 0.1 ohm resistor) and an op-amp based comparator circuit to indicate when it has reached it's end-point/cannot move any further.

Measure the resistance across the motor terminals (this is assuming a simple 2 terminal DC brushed motor) with an ohm-meter. Then you can estimate the stall current by Ohms law, V = IR, meaning I_stall = V_applied / R_motor.

As the motor begins to move and starts generating back EMF, it will reduce the input current to something more reasonable.

When the motor meets something which stops the output shaft from moving, the resistance reduces again back to the motor's armature resistance (R_motor i mentioned earlier).