Age is a file encryption utility that is more robust and easier to audit than similar functionality in GPG. Reputable people like Str4d and Matthew Green are involved. A rist implementation is in the works. Str4d is working on a GUI, has already packaged it for Debian and also has a Rust implementation. A container mounting fucntionality is planned. Let me know if it interests you to include it and I will open a phab ticket.
Codecrypt can do symmetric encryption too and I trust it does the same great job it does with asymmetric stuff.
I guess the only difference here is we have a point and click GUI application for file encryption. If Zulucrypt works then there’s no urgency.