Repurpose old phones as a server

The Octo4a project :
use as a 3D printer server , webinterface , time lapse camera , and more
https://hackaday.com/2021/12/04/finally-a-use-for-old-cellphones/

use an old cell phone to monitor very long 3D prints

Back in 2014 or 2015 I rooted my old android phone, then I copied over a debian image in a file. I could then mount the debian image and chroot into it, giving me a full fledged debian system (with limited hardware control though).
I mostly used it as a downloadbox, and accumulated a respectable over 300GiB of films over a few months.

use old cellphones as security cameras as well as a monitoring camera for my 3d printer. They all had bloated batteries so I took the battery apart and removed the circuit board, soldered a micro usb connector to where the battery used to connect, then put all of it into a 3d printed frame to act as a drop-in battery replacement that converts the phone to being usb powered instead of requiring a battery like most android phones. This both frees up the USB port for other uses and makes it so you don’t have to replace bloated batteries anymore from having the device plugged in all the time.

A lot of hardware muscle going to waste.

the python issues is only a small part of the hurdle .
significant for this particular project (though it looks like they are solved nicely). for using old cell phones python would be the least of my concerns.

Apart from rooting the phone and being able to (let’s say) compile C code, the big show stopper for most projects is the need for IO, which frankly is the handiest thing about whatever single board computer you can buy for a few dollars. If all you need is USB (like this project) a phone is a viable choice.

I use old cellphones as Squeezebox players, since many years. As the Logitec Media Server is free, and runs everywhere, you can míx Windows, Linux and Android clients, and even let them play in sync

Squeezebox : network music streaming player , either from home network or from internet
https://en.wikipedia.org/wiki/Internet_radio_device

I’d like to use a mobile phone with sim card as a gateway to the cell network and be able to have it receive an SMS or phone call and pass it on to another android phone (without a sim & via wifi) as if that phone acted the very same as the gateway ie get SMS, reply, get phone call, make calls just like an ordinary dect type extension :
 sigh: looked around none I’ve found :-/

the reality is that unless you need a screen or camera a r-pi will do the job much better than an old android and you don’t have to do a dirty hack even if you have rooted and loaded LineageOS.
It is cool for a person who is ultra poor and/or without a supply chain but is so much work for someone who can afford $5-10 of hardware and have it show up in a few days. Usually even for the poor a phone that works is worth more than $5-10. This project is cool like the ironman power armor suit built in a cave cool.
Android hardware is poisoned by the unavailability of FOSS drivers so we can never do what we want and are held back to kernels which support the released closed blobs and requires the dirty libhybris kludge unless someone does deep i/o analysis and makes an unofficial FOSS driver.
Cool hack but apple/androids are trash on delivery day, support and contribute to hardware like Librem or pinephone which only builds from hardware with FOSS drivers available.

hued cable (https://ihued.com) so that you can use the phone as a garage security camera and also use it to open/close your garage door from anywhere in the world. Very useful when I forget my keys in the house and when I need to let in my neighbor to feed my cat when I’m on vaca…

I’m a big fan of installing a chrooted linux distro and using it as a small linux playground. I recently set one up as a DNS based ad blocker (similar to pihole) using blocky (go based). Couple it with a musl based distro and you can use fairly recent software even if your stuck using a very old android kernel.