Nextcloud is feature-rich, but a little slower and vastly more complicated than a CalDAV server like Baikal.

Use a hardened-by-default OS like OpenBSD, HardenedBSD, or something similar in Linux.

Uh, can't you just log in to online banking through a browser? I can.

Grep. If you have the sources digitally and local, you can just run a search for a string.

It involves a learning curve, and some things don't work like bluetooth and streaming copyrighted movies. But most everything else works. Many things in AUR would not be there, but alteratives exist for those willing to adapt. Setting things up are typically done by editing text files on the command line. This sounds hard, but is actually simple once you get used to it. I tried Qubes last year out of curiosity and found it hopelessly convoluted.

Laptop not a server, huh? I am writing this from a laptop running OpenBSD, which is my main work and play machine. Works great.

Thanks for the explanation.