Not sure if I understand.
Under integration > entities I see the option ‘display precision’ for sensors. (sensor.hb_temp_inlet). This option is missing for a number entity (number.hb_2_fan_speed)
Which UI settings are you refering to?
Did you create this “number” entity by yourself? Or it is created by some integration?
If by yourself - then did you set a “step” value fractional?
If it was created by some integration - you can create a template sensor for this “number” entity with a desired precision.