It’s a good question. For now I’m still working through a few books that I had in my backlog that are available on Project Gutenberg.
I’ve been looking around for a few ebook stores that sell books in epub format, but am struggling to settle on one. I do want to buy and not pirate them as much as possible, but most people seem to point me towards ebook piracy sites whenever I ask.
I’ve Obsidian Sync set up so that my Obsidian vault is synced across all my devices. I don’t do much input into my vault on the Page, but mainly use it to view notes I’ve already written, or to keep my TODO list open while I do other things throughout the day.