That reminds me of my own Samsung Galaxy SII. Shipped out of the box with Android 2.3, Samsung supported it up until Android 4.1, then I switched to CyanogenMod until my father rage-bought me a new phone in 2016 because it crashed so much he had trouble contacting me. I still kept it up to date with LineageOS and then unofficial versions for fun (it's at Android 13 last I checked). Do I expect a Samsung Galaxy SII to…
Even that was amazing for Samsung's standards back then.
For example my former Samsung Note II shipped with Android 4.1.1 Jellybean and they only supported it till 4.4.2 KitKat. Just let that sink in. I basically bought a flagship e-waste device.
Custom ROMs didn't help much since you'd lose S-pen functionality if you went past 4.4.2 as modders couldn't port the needed firmware blobs past that kernel or something like that.
Oh, and also, using custom ROMs could brick your wifi from working as the FW of the wifi chip was tied to Knox tripping the e-fuse on custom ROMs, so then you'd need to use some voodoo to patch wifi back. That is, if you were lucky and your phone wouldn't brick itself due to the FW bug in Samsung's eMMC, that would lock itself to read-only mode out of nowhere.
Seriously, fuck Samsung for that PoS phone, fuck them in the a**. That phone should have been a lemon recall with full refund to consumers.