

BTRFS and ZFS both use block compression, ZFS by default. It’s meant to increase both storage efficiency and access speed and has nearly zero impact on performance. The files aren’t compressed from the filesystem point of view, which would satisfy your requirement not to need any other tools.
I’m confused about your statement that you don’t want to save space with compression, but you indicated that you want to “make the most of your storage”. Are you looking for long-term archiving?

The trump comments aren’t the issue, it’s Proton’s acknowledgement that they will turn over data to the swiss police when asked.