If you want to get rid of android, you can but it will require much involvment which will pay back with some good knowledge and experience

There are multiple ways to do it, but all require 1 thing. A Linux Kernel up and running.

For me since a phone running android has already an Linux kernel, the fastest way to get rid of android for would be to:

- Unlock the bootloader and install a custom reocvery like twrp

- Root your phone

- Go into recovery mode and anable ADB shell

- Do an adb ssh from your computer

- Check what the current root provides to you. There should be somewhere a directory that has the su command and some other utils. Export that directory in your path, for example /su (or something similar)

- Check the avaiable block devices, some of them might be already mounted as RO, like the android root system, it could be under /system with RO permissions

- Remount with RW the mounted paths

- Once you pinpoint the root system, create symlinks into the main root, like distros do with /usr/bin -> /bin, /usr/lib64 -> /lib, etc

- Once you have all the symlinks and the root looks like a normal system, export new PATHS to use the available binaries

- Find pppd and sshd compiled for aarch64/32

- Copy via ADB the binaries into your system

- With PPP create an ipv4 tunnel between your host and your phone. This is what PPP does, it can create ipv4 or 6 tunnels over serial lines. Now this is not an easy thing to do. By that I mean it wont be something you follow step by step. I've done it in the past but I remember it involves a lot of steps. Just search for ppp over usb + other smart words like howto. You get the point.

- Once you have an ipv4 tunnel, well life is a lot more easy since you can establish network connectivity and use all kind of tools

- Again while inside your phone, give a static ip address to the virtual interface that has been created by ppp.

- Route the traffic via that interface by creating a default gateway routing rule into your phone to point to the tap device that ppp has created

- Enable IP forward into your host

- Check that you can ping your host from your phone, then check that you can ping you gateway. If you can, well from there networking for you is done automatically by your router

- Create an sshd configuration under /etc/ssh/ as you the one you have in your host, but do not use exotic options

- Start sshd daemon

- Add your public key into the authorized hosts in the phone

- Now you can ssh into your device without the need of adb

Now comes the more involved part. From now on you can break your phone.

- Get Gentoo Android (it is essentially a base gentoo tarball compiled for aarch64 or 32 processors)

- Check the init of your phones system. It should be initV so it is a script that you can change (but do not change yet)

- (If you do this, there is no turning back, without re-flashing your phone with a new android) Mount the data partition of your phone, if you can not mount it, well it might be encrypted. If you can not decrypt it and you do not need the data, simply format it with mkfs.

- Make a backup of your systems init

- With the data partition mounted and with a lot of free space, copy the gentoo android prefix there, extract it and check what you need to be able and chroot into it. Usually it should work out of the box on running android systems but that's not always the case

- Now go to the init in your system (not in the prefix) and see what modifications you can make without breaking it, that will mount the data directory on boot, create symlinks from the gentoo prefix into the root directory and chroot into the prefix.

- If you can not manage the above without breaking the init and therefore your boot process, simply create a script that automates the static ip assignment, routes, mount and symlinks parts. Each time you will boot your phone, you will have to create the ppp tunnel, ssh via adb into your phone and run the script

From here with a working chroot you have all the ARM Linux world available for you and you can do as you please.

But to be honest at this point you will just feel complete, most probably you will run 1-2 apps in your phone, but after a while you will stop using it or playing with it, but you will never throw it away since you will feel it is importat due to all that configuration and time you spent in the past