Ive been on the hunt for a while for something like this. I started looking again since the life360 breach. This is nearly perfect. Just need the iOS app to have a little more support and be in the app store for my less techy friends/family.
I use masked emails for everything. Either thru fastmail.com or the proton.me one
If I recall phonetrack shared everyone with everyone. I like this Locus because its a one way share. So my brother can see where my wife is. But I can see where both are. I also like that its not Dependant on my infrastructure.