Yeah, it might be able to go newer, but as I said, Android is an alien land to me, and what I seemed to find on XDA Forums was that this particular model of S4* is only supported as far as 14.1. There’s so much info out there that it’s too easy to get overwhelmed, so I got to a point that enabled what I needed and left it. Willing to accept any further advice, mind.

*Turns out there are several variations of S4, ranging from the I9500 Exynos processor one I have here, to several different versions running Qualcomm silicon.

Its hard but rewarding, and perfectly doable given you want to do it.

Note that there are a few mandatory requirements for a port to be feasible, like unlocked bootloader and vendor sources available for kernel.

As newby, you also want already existing ports to start from.

Also, some powerful hardware to build on (32+gb ram, 10+ cores, 100+GB storage).

Also older (up to A11) can be real bitches, after A12 things are improving a bit.

You need to copy or grab or create the device tree files. Usually by cloning a similar device. Vendor files are extracted from stock rom. Kernels, you need an official release from vendor to start width.

When we're talking about devices that aren't getting security updates anyway, you shouldn't be using them for anything sensitive, even with direct lineage OS builds. Without baseband hardware driver updates, you're an extreme risk for a drive by exploit.

From my threat model perspective, lineage OS makes a vulnerable device useful, but not for anything sensitive.

A game phone, a VPN phone, a webcam, a sync thing endpoint, a crypto miner, a kid's phone, lots of uses. But not banking, not passwords.

If the build isn't coming from lineage os, I question why not? It just takes one maintainer to keep the build going. At best you're going to get a point in time build, you're not going to keep getting operating system.

Samsung and the carriers. The easiest way for most people to get a phone is on a carrier plan but surprise surprise. They OEM lock devices so that users can’t swap firmware or root. Doing so would allow them to go to another carrier. As if hanging a lease contract over your head wasn’t enough.

WiFi, mobile data, Bluetooth and VoLTE all still work fine. Performance and battery is about the same as when I used oxygenOS11 for about a week before going to lineageOS. Only con is the need to wipe the phone so make sure things are all backed up! I missed a few folders and photos before wiping the device.

OnePlus 7 Pro owner here. Currently running the Pixel Experience ROM. Pretty stable. Although I haven't really tried NFC as there no use for it where I live. You can check out the xda thread.