Hi. Not sure if anyone is still interested... but I'll share my real-life results. I live in a cold northern climate, last winter -- my band and I decided to try remote practice software to alleviate driving to practice when there's a blizzard out. Spoiler alert: "it doesn't work". I'll elaborate.
We tried every solution and every piece of software out on the internet. In today's world, it is not impossible to do a remote practice with Jamkazam -- or any of the others. Latency is the problem over the internet. With my band.. we all had super high speed cable modems.
What IS possible is the following: You can use Jamkazam.. or any of the other software to do online "Jamming". "Jamming", is the art of playing a repetitve pattern over and over. I.e... .think "ii-V" progression. You can jam with many people over a common repetitive pattern that you are playing. What happens (and this is hard to explain), is that you are actually playing in the pattern seconds late. So it all comes out ok... because the pattern is repeating over and over. But this is different than playing a song with changing chords. As soon as you try to play a "song", your latency will kill it in a matter of about 2 measures. Because of the latency... each person on the live session hears the music "late" and it is impossible to play along with it. So if you are willing to play with a pattern, and a metronome helps... you can play a repeatable progression. Hence this is why... all of the remote practice software has the word "JAM" in it. You can "JAM'.... but you can't practice a song.
With the advent of 5G... it may be possible to do online practicing if you are in the same city. 5G promises low latency. We'll see.... promise and implementation are 2 different things. In our mortal world, it will never be possible to have a remote practice with 1 person in San Francisco and another in Boston. The speed of light is 70ms... and that is our "earthly - mortal" reality. 5G or 500000000G will never beat the speed of light... and hence we will always be limited to some distance as communications speed up.
But... "jamming" online... to a repeating phrase... is kind of cool... but it does get old after a few measures.