It sounds like you're trying to make something like: https://github.com/cryptomator/cryptomator

It takes the files that you want to store in the cloud and encrypts them into a bunch of individual files (like encrypted archives) and uploads them to the server. When you access the files it automatically pulls down the archives that contain the files that you want.

You just see a regular directory that's being synced with the cloud, but the cloud service provider only sees you uploading a bunch of encrypted files with nonsense filenames.

There is dmcrypt that basically does what you want. IDK if the implementation is in kernel space though. It works through /dev/mapper if that matters.

I do have this idea that you can save encrypted files to a cloud server and pull it out and unencrypted by a light weight program

Sounds like Cryptomator would work for you.

KDE has built in "vaults" now that sound maybe like what you're looking for.

Storing files encrypted and decrypting them on-demand is called "encryption at rest". Linux supports it but is not enabled by default. You can also encrypt /boot to get FDE (Full Disk Encryption) to ensure that the kernel or bootloader is not tampered with. Look into LUKS