I caught that deal some time ago where a subscription to CuriosityStream would also grant you a sub to Nebula. I love Nebula, in theory - I spend a lot of time listening to video essays, and I love the quantity and quality of creators there. But the android app has a lot of buffering for me, and up until the last time I'd used it, it wouldn't remember my watch history / where I left off, making it really burdensome to watch long essays there, so I always just opted for YT Revanced. Just now, I went to check, and the app seems to remember my progress in a video so...!! I guess I'll be giving it a second serious chance! :D
I tried watching some stuff on CuriosityStream, but I've gotten so used to YT-style essays and documentaries, that now anything that has costant background music and fast paced montages kinda bugs me out, lol. But if you like classic-style documentaries, there's a big catalogue, I'd recommend it! Overall, I think it depends on how much you pay a year - I think I pay around 15/20$/y and I think it's a steal, even though I enjoy but a fraction of what's being offered to me. If I used it more consistently, I'd be happy to pay double.
For me, yes. I notice that whenever I'm reading on my phone (night mode, blue light filter, lowest light setting), I will stay awake longer, my eyes strain, it takes me longer to fall asleep. When using my kobo (not backlit, but still lit - it has those leds all around the screen that light it up from above!!), it's like I was reading a paper book, except I can read in a dark room without any strain to my eyes whatsoever, and I can take on any position without having to adjust the light source!!! An absolute game-changer in terms of comfort. In fact, I think my eye strain is even lower with the e-ink reader compared to regular paper indoors, because I have a better light source no matter where I sit in my room.