Debian-based custom built thing. Nothing special.

I have no such advice. I use a Linux basedd NAS myself.

What are those categories/apps?

Seems you also use a bit of freeBSD in your setup besides Linux. Still FOSS though!

Sorry I really don't follow what you wrote in that comment. Can you write something coherent and with references to sources?

What is the problem with GrapheneOS?

As a medical doctor I strongly object to this. Generics are tightly regulated. The substance is the same. What can vary is the binding materials and alike. In very, very rare cases a patient can be allergic to a substance that is specific to a certain brand (and not part of the active substance). This has happened to me only twice. In some countries anticonvusants are the exception where generics aren't used, but that is not practiced everywhere.

Everywhere possible. For SSH sessions, logins on the Internet. PGP and chat apps. All the time.

Nothing really. You pay with your time by going to Linux but the effort is getting lower both because of me getting better but mostly the experience won't compare with 20 yeara ago.since the non FOSS alternatives are getting more telemtry/call home functions rhe choice is an easy one.

Used to use Windows 98 SE. First introduced to Mandrake Linux around 2000. Had no Internet, got the install media from a friend of my father. Barely got it working and couldn't read English. Went back to Windows XP. Ubuntu came. Began to use it around 2008 for a few years. Back to windows briefly and then Raspberry Pi was launched. Switched to Linux permanently.

Almost went back in 2013 due to Lightroom, gaming and a few work related medical software.

Began to grasp FOSS maturely in 2014 and switched to alterbative software. When Steam launched Proton there was no turning back.

I was obsessed but it has come and gone. Now I'm a bit of a nuissance to friends sllwly switching them to alternative software. My partner gets the worst treatment. Now she uses hardware security keys, assymetric keys auth etc

You should care about Linux. The web depends upon it :)

No problem. It probably won't be the one you end up with if you stick to Linux for a couple of years but as I said don't distro-hop. The big jump is the one to Linux. The difference between distributions isn't that important. Good luck!