Not the only, but possibly the best available. You didn’t try other options, though.

If you didn’t start from scratch you can’t be in control. Simply said. Also, the most difficult part is hardware and chipset drivers, stable supply of parts and so on. It’s not that easy and no wonder to me why it takes literally an infinite amount of time to get a “linux phone” going - aaand keep it up.

It will do another 7 years if you keep it away from humidity. There are three things that are important: the membranes, the battery and the material quality of the chipset. If those three are kept in shape (can’t do much about the chipset) there is no reason for it to fail. I have got a Uboom running since 2014 and it’s still blasting. I met the inventor once, we talkked a long time about his product. Uboom weren’t on the market then.