I was able to just install F-droid and from there get Obtainium to import my usual apps, including Librera which I prefer over KoReader. No jailbreak necessary.
However… I do eventually wanna jailbreak it and get Amazon’s presence off there entirely if I can. Thanks for the references, for when I get there.
Just letting the more non-techy people know that you can get FOSS apps like KoReader without having to go all the way, so to speak.
Oh, yeah, it is a Kindle Fire. I never got into e-ink.