Activists should not be using email for activism at all. I agree on mullvad for the VPN. This video does a good job explaining the issues with email for people who need privacy from groups like governments : https://youtu.be/iH626CXyNtE
I also question recommending signal over one of the decentralized alternatives like matrix or simplex, though really that's probably fine.
Why ouroborous over watchtower for docker ?