You are a fucking idiot. Obviously It is encrypted If both people are on the same provider. Otherwise you can just import a PGP key and use it that way. 
The fact that you are telling people to self host but at the same time selling your own VPS solution as “self-sovereign” is exploitative. 
People will see through it and your “businesses” will inevitable fail
So fuck off and try scamming people somewhere else 

 It is not END to END encrypted unless the same provider.

Therefore:
You are promoting centralization.  Everyone on the same provider.