can Android be decompiled and have an os thrown on?
 

It has the kernel so can't that be kept and other parts taken off while as root? Then throw on an os and reboot, right?

It can, and has been. They're called mods, e.g. Cyanogenmod. Yes it has the kernel but it goes to some lengths to avoid giving root access. It's best to see Android as a separate google OS.

Start thinking about what software you want to run. What OS does that need?

I recently heard that attempts to monetized Cyanogenmod had not gone well and that, as a result, the project forked. I haven't heard any recent developments, but I do know persons who have routinely used it for years.

Later:

Because of the above, if you want to use Cyanogen, I would recommend research doing your homework before deciding what to try.

I considered rooting my old phone.

CM12 is up until the year's end. No promises thereafter. There's redundancies, and I get the impression the original genius may be missing, or simply redirected at another goal. Finance is an issue. There is a fork, or rather a successor, but no release from him yet. What it needed was someone like Samsung to absorb it, but that never happened.

It takes one kind of guy to make something work - the genius & effort that go into creation is one thing. It takes another set of qualities and a level head to stay in the one place maintaining and slowly improving adding features to that code. In this case, the linux OS is changing continually, as is Android. This is a huge mental drain for the genius creator kind of guy who wants a challenge.

Some of the people from CM have set up Lineageos and are carrying on. They've got plenty of ROMs on their site. Check it out. I'm actually using one of their 'overnights'.

Let's hope they make a go of it. What was really good about CM and indeed other mods was the swift response to security issues. It's difficult to make a financial success of that lark.

I got myself a new phone recently with Android-7.0, but it knows more about me than I know about it :-/.

These responses imply messing with Read-only memory, as I've read about LineageOS.

My idea was find a way for root to be used to to rm tons of stuff, have some kind of app/download start writing the OS onto storage memory, and then reboot. The kernel is there as are the modules. I don't know how practical that is, but I think it would be. There shouldn't really be a need to directly mess with hardware.

source: https://en.wikipedia.org/wiki/CyanogenMod

Why would firmware need to be messed with? The kernel is already there... just get root and the rest should take care of itself, right?
I mean, ok, a lot of phones probably have variations in their kernel, but I reason there is something similar amongst them that should allow ease of transition.
source: https://en.wikipedia.org/wiki/CyanogenMod


As an aside, but not so relevant, the most complex thing I've read of was how someone found a way to take a Windows install, decompile it, thrown a Linux OS on, but it could only be sustained until a reboot. So, I believe well enough that since the kernel and modules are already there (thus, no hardcore reverse engineering needed if at all), then all that's needed is getting rid of a bunch of the software and over-writing it with the OS. My familiarity with Live Linux OS's leads me to believe it should be easy enough since the kernel and modules are already there.

I had a G1, or the European equivalent back in the day. I rooted it and installed CM, but even with root I couldn't do much. There's a lot of your questions answered on xda-developers.com/
I don't think so. Android has a kernel, not necessarily your desired kernel. By firmware I take it you mean the niggly bits linux doesn't have - like software for phoning, radio control, drivers for all the chips and clever functions, graphics, sound, etc. That's actually the OS. Firmware is software for the intelligence in peripherals, loaded into the peripheral. That's not necessarily the case with today's phones. It's best to think of them as less powerful computers. The sound chip or GPU may have firmware, and you're right, no need to mess with that.

I found the "Paranoid" OS on a Chinese site which was Android with ALL Google software removed. Didn't work on mine. Good try though.

Lineageos doen't load any GAPPS unless you do so separately. You need a minimum GAPPS for the playstore downloads but if you don't want that you don't need to install it. But android is a google system so there's some google in there anyway.
Unfortunately google seems very difficult to avoid these days.

Google is basically impossible to avoid these days, but OTOH they have so much data on everyone that what can't be done automatically isn't done at all. They must get terabytes of data from Android systems. Pity the poor bugger sent in to find what one user is getting up to over the last 3 months!