The answer is absolutely yes

Keep in mind that RSS is just some XML sent over HTTPS connection. For anyone outside, it will look like gibbirish, they can say you are requesting and getting some things from that particular site but not what it is.

Except I was not born yet when pagers were a thing

We didnt have any kind of phone when we were in school

There are no shortage of encryption software in the market, use one, any one, Veracrypt is fine, so is million other software for this.

Use a note taking app like Joplin, Obsidian, though not open source is just as fine. Sync its data folder to the encrypted vault created with encryption software of your choice, and you are good to go

It should be illegal if they do not call the police afterwards they are done with their personal justice

How do they define what a social media is?