Not disputing that it’s good, it’s just so much stuff is built to work with KDE or Gnome that I think you’d miss out on using E.

Enlightenment has been around for decades, and it was quite a bit more popular in its early days because things like KDE/Gnome/etc weren’t the de facto DEs pretty much everyone used like they are now. I used it back when I had a linux box like 25 years ago and it was great, it was very slick and pretty, but now so much is written for KDE/Gnome that it feels like using anything else is just asking for trouble.

UpNote. I use it like a combination of the gollum wiki described by OP, but I just put everything in there. I have watch and reading lists for things I want to check out, writing projects, notes for TTRPG games, I keep extensive notes on healthcare-related stuff, and so on. I like UpNote because it’s lightweight, has windows, linux, and android apps, and because it has a one-time $25 lifetime membership that does free syncing forever instead of a monthly subscription like most other things seem to. I’ve tried OneNote, Evernote, Obsidian, Joplin, AnyType, and a bunch of others and didn’t like them for various reasons, but UpNote is both pretty small and also has a pretty full-featured editor that can do rich text, all kinds of formatting, media files, etc.

The only thing I’ve run into that UpNote wasn’t ideal for is I started writing a novel a couple months ago and managing the structure and notes and all that got a little unwieldy so I picked up Scrivener. Still wish they had an updated linux client or there was some good, complete, feature-rich linux-native equivalent, but it runs pretty good under wine, so.

To be clear you don’t have to get that technical to read non-Amazon books on your kindle… I’ve owned 2 different kindles over the course of about 15 years and literally never bought an ebook from Amazon. Just gotta know where to get them (libgen) and how to use them (calibre.)

A cheap ereader would be nice, but I’ve kinda had to go the opposite direction; my eyes weren’t great to begin with and have only gotten worse with age, so I need a larger screen. I do very little reading (in general, not of books specifically) on my phone because it’s too small and I have to zoom in and pan around all the time, etc.