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.
OpenSMTPD. I run a private mail server for family, and it works flawlessly. No maintenance aside from backups and occasional OS upgrades. https://poolp.org/posts/2019-09-14/setting-up-a-mail-server-with-opensmtpd-dovecot-and-rspamd/
Grep. If you have the sources digitally and local, you can just run a search for a string.
Don't use Outlook for non-Outlook email services. Problem solved. I am required to use Outlook for my work email, but I keep all of my personal email separate, accessed with FOSS email clients.
Care to elaborate on the significant downsides?
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.
If Hugo stops working down the line, you can compile your markdown with something else. Simple is king!
My OpenBSD operating system on my laptop is set to randomize my MAC address at every boot.
OpenBSD
Doesn't work with Javascript blocked.
Nextcloud is feature-rich, but a little slower and vastly more complicated than a CalDAV server like Baikal.