I only met techies who cared about continuing to use a phone if they could only boot from their SD card. Regular people don't know about the option.

So consider that this niche feature you find useful is of almost no consequence to anybody.

Additionally, iPhones and Samsung devices have really durable internal storage. Almost always the battery craps out first.

It's not about trying to boot off the micro-SD card, it is being able to just pop out the card, and get all the data that was stored on it.

Well sure but most smartphones -- both iPhones and Androids -- do periodic automatic cloud backups.

The ability to do offline salvaging does not seem like such a big selling point to me.

I disable cloud updates for privacy reasons and bc backups of that size would cost more money than my own solution

As for offline salvaging, do you realize how many phones have had bugs that resulted in boot problems in the last 10 years?

I do, but I am not sure what can I do -- Androids are no longer an option for me because Google is way too obvious and they collect everything they can, 24/7. It's too much.

As for privacy, I would disable cloud sync and backups as well. But eventually came to the sad conclusion that I have a lot more going on in my life and I cannot sacrifice even more of my preciously little free time to self-manage all my data -- not to mention this would require a moderate investment in my own NAS / 10Gbps switch / 10Gbps router and end-to-end encrypted backups to 1-2 VPS-es.

I get where you are coming from, I do. But I had to make a choice between an actual life and paranoia. I settled for a "mostly ok" solution and a bit more of a personal life and free time.

If privacy and offline-first own personal data get commoditised, I'll be the first to switch away from cloud (and thus Apple).

Some Samsung devices have removable batteries, which if replaced with new ones, can add some more life to it.