Yesterday I did some evaluation testing with a few devices, notably PIC16LF1904, PIC16LF1934 and PIC16LF19175 that are largely pin for pin compatible drop in devices. 1ku pricing is $1.18, $1.46 and $1.19 respectively. All are available in 40 pin 5x5mm UQFN, but I used the DIP variants for this.
The best I managed so far at 3V with the display operating but with the CPU in sleep is on a PIC16LF1904, at 410nA plus 14nA per on-segment with the display attached, in static mode. This was using the internal LF oscillator, but no RTC functionality (I don't believe an RTC is a requirement in this case).
Measurements are taken with a Keithley 238 SMU and triaxial cable assemblies to the DUT. The MCUs were on solderless breadboard, and the debugger and any other probing removed. The LCD is DE 117-RS-20/7.5 soldered on a breakout board that had been cleaned in an ultrasonic cleaner.
As usual, you should never trust the datasheet when it comes to low power current draw specs: sometimes it's better, sometimes it's worse, and often the difference is dramatic. Judging by the quality of the quoted figures, I strongly suspect they use unsupervised interns on this work. Measuring sub-uA takes care and attention.
I found some interesting facets regarding the sleep currents. Sleep currents are important because they can be a show stopper before you've turned on a single LCD segment.
The typical sleep current for the PIC16LF1904 is listed as 160nA @ 3V, I was measuring only 17nA. The same applied to the PIC16LF1934 where the datasheet quotes 80nA @ 3V, and I achieved 16nA right off the bat. It's times like this you question your own measurement skills. Replacing the PIC with a 10Mohm resistor gave expected results, allaying any fears of a gross operator error.
On the other side of the coin, the PIC16LF19175 (a recommended replacement for the PIC16LF1934) measured 275nA at 1.8V, but at 3V it was a very different story, with in excess of 3uA (spec says 350nA). It's not clear to me why this is, but after spending half an hour tweaking I put it to one side, and concentrated on the PIC16LF1904, and getting the LCD operating.