I have an e ink smartphone, specifically a Hisense A9. It has the same screen as a Kindle. It is wonderful for productive stuff like reading, messaging is passable, and videos are pretty much unusable. It's wonderful, I've read so many books now.
If it is to be used as a "reader" device then, well, whatever. But in that case why not just use a "reader device" then.
Which there are much cheaper options in the same form factor! The InkPalm 5 is 1/3rd the cost. Neat little gadget too.
I'd rather work on my paranoia than on getting a fully secured device.
By the way, I am writing this on a mobile with 2 GB RAM and running Android 9 as my other mobile got broken.
Part of me thinks I should just go for it, because I read a lot on my smartphone and miss Android’s Moon+ Reader - with Goldendict for Startdict/Lingvo dictionaries, it made a killer combo for reading foreign language texts with many new words.
Videos being unusable would be a fantastic QoL feature.
I've tried reading on phones, reading on tablets, etc, and the problem is that there's always so much else to do - or, at least, things that interrupt you (SMS messages and such on a phone).
I moved... oh, 10+ years ago, I think, to a Kobo (e-ink reader, not Kindle, far more hackable and open, swallows everything except some DRM which I strip on a desktop). I now have several, as they're just such good devices for reading text. I've also moved a lot of my "web reading" to them via Pocket, in which I send a link to Pocket and get the article, on my device, as long form text without any of the nonsense that's in most web articles (most images work, but not all).
It's far better than trying to have a combo device. And my 10+ year old Kobo Auras still work just fine for reading.
I also have a dedicated audio player (Shanling M0). Great for listening to an album before sleeping or for focus sessions.
I prefer having dedicated devices. The phone is only for communication, taking photos, and quick browsing. And some of the desktop apps I use have their mobile counterparts so I can do a quick tasks without getting the laptop. And I think that suits its main purpose for me, a PDA.
I use the phone as a 4G hotspot, Apple Music, plus apps such as Uber, Waze, wallet, etc. No social networks (LinkedIn and Reddit only on desktop browser), no messaging.
Apple Watch replaced with Casio GShock (solar powered and automatically adjusted via radio, expect it to last 20 years)
Palma has WhatsApp and telegram, outlook (closed most of the time) and reading apps.Podcasts too.
Most sites are consumed via RSS. PDF to Readwise for read later, notes on desktop Obsidian.
I can use Organic Maps in the Palma, and most tickets via QR. I try to force myself not to use the iPhone at all on the street except one of those cases (recharge public transport ticket, camera, payment, etc)