

You can use 7zip to archive files into a .7z and protect it with a password. 7zip is cross-platform, it’s available for Windows, Mac and Linux.
Edit: sorry, I see you have already evaluated this option. I don’t know another method that would me more transparent.
I am a project manager for an automotive part maker.
My job is emails, tickets and meetings on the computer all day every day.
My job is to make sure the engineers work on the correct tasks at the right time. I am responsible for the planning and delivering on time (delivery is a part with mechanical, electronic and software working together correctly). I am responsible to keep the project within the budget. I decide on priorities, what the team needs to be working on first, second and third. I am responsible for making the team work according to the quality process, which means they must follow to correct steps, design rules, reviews and create the appropriate documentation.
I can tell you, sitting in front of the screen all day, is harmful to health (in a different way than a physical job is). For example, almost everyone I work with is wearing glasses, my own vision has degraded a lot.