I quite like Shelter [1]. Shelter apps are installed in a separate work profile, which essentially sandboxes it from the rest of your data. It also has a neat feature to automatically disable (freeze) specific apps and seamlessly re-enable them when you launch them through Shelter.
This is what I do too. If i need to use or test something i don't trust then I use an old phone. All of the phones use crDroid(1) and I have scripts to quickly wipe and reinstall the OS whenever I need a full nuke.
[1] https://github.com/achalmgucker/Shelter