Not even a browser? Shades of Facebook Zero. Only worse, actually.
KaiOS sounds even worse than I thought. Kickbacks like that should be illegal, as should jailing the phone from the purchaser. They probably are illegal under some competition law no-one has enforced since the mid-twentieth-century.
PostmarketOS sounds much more promising! I will modify my statement, then: people who can only afford a feature phone would benefit greatly from a compatible Deltachat client, but they need a decent copyleft feature-phone operating system first.
I can think of several funding agencies that would fund that, actually. Rooted phones are fine to play with, but I think we need OEM support for open OSses for mass adoption.
Offtopic, but I was just using the Pinephone as an example cheap-end Linux-default smartphone. I have a (secondhand) Pinephone and it is very slow. Being able to hack it mitigates that to a surprising degree, though. The slowest thing I generally use it for is this forum, which sadly is read-only if you disable Javascript!
Being able to leave all your messages on the (non-Chatmail) server and fetch them as-needed might be useful for a feature phone with less space than the server.
It has a browser, but the web is not made for those T9 keyboards, so navigation websites is not ideal, not to mention that the browser in the version I tried (kaiOS 2) was pretty old, like Firefox 49 or sth. like that.
And they have a somewhat open appstore, though there are rumors that you need to include ads to be accepted into that appstore.
I contributed a bit to the banahackers community, we made a wiki https://wiki.bananahackers.net/ with guides on customization and app development and our own 3rd party appstore BananaHackers Store
well the phones are like some game consoles, some of them may be sold at a loss to be cheaper and you try to make the money elsewhere, like with paid preinstalled apps or advertisement.
Game consoles usually make their money back by overpricing their games. Printers are also sold at a loss and the toner is sold overpriced to compensate, it is a common business strategy.
(even if I personally don’t like it in most cases.)
In theory maybe, but space is so cheap nowadays, like the cheapest new SD cards and USB sticks I can find have already like 64gb.
Also I can say with much certainty that the core team will not develop that, it would require big changes of how the app works and would also be against the offline first principle and the principle of only using email as a dumb transport pipe.
Also it would likely be cheaper to buy SD cards for the people that have this issue, than how much developer time it would cost to develop and maintain such a feature. Which would by the way have bad UX, like you won’t be able to search offloaded messages, since they are stored on the server in encrypted form.
Other than KaiOS, the other category of even cheaper and more power efficient dumb phones (S30+) are running said web apps under the hardcoded Opera mini browser.
Only the best web apps can be ran under such restrictions, but it is possible - I’ve even made games for it. It restricts you to the engine of Opera 12 (ES5 with a few further oddities) and the web app must react within 5 seconds after each interaction and serialize its state between interactions.
Shades of Facebook Zero. Only worse, actually.