I can only speak to anything using MultiFunPlayer and do also wonder, what kind of interpolation non-T-Code devices use.
In MFP the user can choose the type of interpolation used (Linear, Makima, PCHIP, Step). Since scripts are time sensitive with their direction changes, I highly recommend PCHIP interpolation, which smooths the movement while preserving timing. To make this point more clear, Matlab has this nice comparison plot for their own implementations of these interpolation methods:
On a lower level T-Code devices can receive a second value next to the target position, either a time interval or a rate/speed. With this it would linearly ramp to the target position.