The Ribbon isn’t the worst thing. It tried to solve the clutter of the previous interface, although I always preferred the old one.

Here is an interesting take on the problem of modern interfaces: https://datagubbe.se/decusab/

Maybe you should try Anytype. It’s Open Source, encrypted, has applications for major OSes, provides synchronization, allows export of documents to Markdown and PDF. Sometimes it’s rough on the edges, but I think it has a potential.

Take a look at DAR: http://dar.linux.free.fr/

It has many advanced functions and is actively developed (for over a decade).