Protect myself from my ISP?

Noob here. This is probably the most repeated question, but I don't know the technical terms to make the appropiate digging online, and thought of asking humans before slopping my way around.

I don't trust my ISP or the government above it.

The ISP remotely manages the local network! So I installed a router of my own and my devices only to that one.

I would like to encrypt (?) anything that goes out of my own router, so my ISP doesn't evesdrop what I'm doing even if they want to (I know I know... if they really wanted, they could just send friends to my house).

Using Linux, Android GOS, and Pihole. They live under a "picked-up-from-a-shelf" router; and that router under theirs.

(I cannot get a different ISP)

Thanks