Measuring power usage over time? What kit is that?

I have a similar application where I was looking at using a Pico as a remote temperature node. It needs to wake up every 30s, take a measurement from 2x DS18b20 temp sensors then transmit the values using a nrf2401. I was looking to run it off a single 18650 battery - but my theoretical calcs say it wont last the 18months I would like it too.

I am making the assumption that the full Pico run current is used while waiting for the DS18b20 to convert and return - or is that not the case ?

Gordon - I saw in another post you mentioned it could be possible to slow the STM clock to save power in run mode - is that something that is implemented/quantified as to the savings ?

I know I should probably also do some practical measurements here, but dont want to spend that time if this is never going to fly.

I have found another little Arduino board setup for this kind of thing which has a 5mA run current - but would prefer to use a Pico as the other half of the project is also Pico based.