I still have an old Kindle and it still gets months of battery life. I occasionally read comics so this may get me to upgrade.
I just got a boox e ink tablet. It runs android. I have a sideloaded manga reading app and Google books installed. epub books (found easily on Yandex) can be uploaded to Google books from my phone.
I love it.
Oh nice! Yeah this is 100% the best way to go. I use the app Mihon for finding/reading manga, its basically the same as tachiyomi before it got shut down.
The one I use is the Boox 7.8" Nova Air2 eReader. I chose one without a color screen. The color screens are cool and all, but for black and white content, the color layer makes the white more of a grey color. For that reason I don’t recommend the color e ink quite yet.
The 7.8" screen is literally the perfect size for manga. It feels perfect.
Good luck!