Observation: How to map decimal values

I see that Observation has value[x] with support for valueString, valueBoolean, valueInteger etc. What I cannot find is valueFloat or valueDecimal. How can I map a float / decimal value for an Observation? Is valueQuantity my only option? I do not really need to specify units etc. so this seems to be more than I need. TIA for yoru help.

What kind of Observation are you capturing that has a decimal value but no unit?

Fair point. There is a unit and I should use it. Sorry for the newbie question :flushed: