(re. using a Weak Signal app with an Analog-tuned receiver. The thread topic has changed, but I'm afraid this will be lost if I change the subject line)
Yes, you can! But it ain't easy.
I used my TS-830S for some WSPR spots when I was starting to learn about it. I'm not sure you'd consider it analog tuned though; it's certainly unstable enough to mimic one if the digital frequency readout doesn't disqualify it. The big challenge is in the frequency drift. The WSPR decoder can tolerate only 4 Hz of drift during almost 2 minutes of receive. And the drift has to be gradual. So... the analog receiver has be of good design, warmed up, and the shack mustn't be drafty....
Next challenge is getting the frequency right. Once you get within about 300 Hz, the computer will display traces representing the signals it hears. You'll know which ones they are because they'll start on the even minute. Adjust the VFO until these seem to be all inside the 200 Hz -wide reception band.
The easiest connection is to let your laptop's built-in microphone listen to the the receiver's speaker across the room. Set it to USB and adjust the BFO and/or filtering so that 1500 Hz comes through well. Next better is to plug a microphone into your computer, put it by the RX's speaker, and turn down the volume. To do it right, though, make a cable.
So...yes, you can decode some spots. The frequency and drift report won't be right, but the TX station won't care because your reports will be outnumbered by ones made with modern receivers.
Your question made me think of a fun competition idea: How old of a receiver can we use to pick up WSPR DX? Or...what's the fewest number of tubes required to decode WSPR? It'd motivate us to haul out those relics and [re-]learn how to clean up those old VFOs! What RX will you use?