“Insular” is a sandbox environment to clone selected apps and isolate them from accessing your personal data outside the sandbox (including call logs, contacts, photos and etc) even if related permissions are granted. Device-bound data (SMS, IMEI and etc) is still accessible.
Isolated apps can be frozen on demand, with their launcher icons hidden and their background behaviors completely blocked.
Insular is a fully free and open source fork of 
Island with the closed source parts removed.
How does it work
Insular takes advantage of the “managed profile” feature on Android 5.0+, which is also the base of “Android for Work”, to create an isolated sandbox for apps with their data.
Apps needs to be cloned in Insular first. Afterwards, the clone can run parallel aside from the original one (even with different accounts signed-in). It can be frozen on demand by Insular. (NO ROOT REQUIRED)
Comments and Reviews
I use it on a de-Googled device for non-privacy respecting apps that I still need/want access to on my phone.