Szwendacz

Nextcloud is reall nice but if you are using many of its functions,. For just calendar it seem a bit to heavy, isn't it?

That probably depends on your vps provider (if using vps). Hosting exit node at home is clearly a bad idea.
Check this (mind that this not have to fresh enough): https://community.torproject.org/relay/community-resources/good-bad-isps/

Any example instance? thier demo instance is down or something.

Yeah, currently it is bad time for computing power donations.

I think I need to do something similar with my cloud. It seem good both for organizing my cloud and for plain visual organizing training.

My config files are my documentation, but what is not suitable to be written in config files I write in selfhosted BookStack

I would not recommend docker-compose for a begginer. As first, one should learn basics, then optionally switch to docker-compose to automate stuff he already know. Also bind mount volumes are a better solution for long term storage than default volumes, since docker will never delete those, and their path in host system is configurable.

Technically any connection made from inside your local network can expose it to the outside world for someone outside. Browsing web, some nasty js and here you go.
I personally have some stuff hosted on my home hardware, cant share details obviously, but even the ip address of those services is not my home ip address. Also extensive use of rootless containers and other cool stuff is making me want to keep things like that.

A living proof how apt can be dangerous.

Don't even try installing steam or you loose all your gpu drivers and stuff.

using apt for managing all system packages seem like a security flaw. If it get corrupted or run badly, whole OS can be destroyed.