Believe it or not, an old smartphone can run on the new Android 10. It’s an unofficial effort but someone was able to run Android 10 on an old Samsung Galaxy S2. The Android phone has been around since 2011 so it’s almost nine years old. An old phone as such is no longer supported but apparently, it’s possible. The support is not official but it’s good to know an old device can handle the latest Android mobile OS version.
On a Reddit thread, it was noted that the Samsung Galaxy S2 has now received eight years of support from 2011 to 2019 since the phone has been updated with Android. It’s the longest unofficial support on a smartphone which only proves you can do a lot with some hack and tweaks on the code or system.
Thanks to LineageOS ROM, you can try running Android 10 on your old Galaxy S II phone (i9100). Go ahead, only if you know how to and understand system-as-root, recovery, ports, and kernels.
XDA Senior Member and developer rINanDO did this and shared his work with the community. ISOlated-RECovery is needed for the said builds.
To start, make sure you boot the device into download mode (Volume down + Power/Standby + Home and hold for ten seconds). Start ODIN 3.07 on your computer, connect phone via USB, press volume up, and ODIN will work. Follow other steps available HERE.