I used the Lumify with low frequency and cardiac probes for a year and then switched to the Butterfly IQ and now IQ+ when they came out. Took several CME courses and worked online with preceptors and radiology overreads until my medmal agreed to cover this (I'm in solo outpatient practice).
Very useful for DVT rule outs, pneumonia, gallbladders, abscesses, post void residuals, looking for hydronephrosis and finding wood or fish spine foreign bodies. Working on my MSK skills still. Lumify was better at cardiac imaging but that's not been a big use for me (yet).
There are some data for looking at abdominal pain for some etiologies but not sensitive enough (in my hands yet) to avoid CT.
We need some academic primary care types to get data showing effectiveness in various primary care problems (most of the data is from ERs) and to clarify how much training is really needed.