Back when I used Samsung, the custom ROM scene offered stock ROMs with all the crapware removed - usually labeled as "debloated". If you can find them, those should allow you to update with your S-Pen still working. You can also debloat Android yourself (sort of; without root it just disables packages rather than uninstalling them) using UAB.

You'd lose KNOX though, and a lot of modern apps deliberately break themselves if you're not running pure stock (or spoofing it, which I can help with if you want to go this route).

I totally respect that take on the matter. I believe its abhorrent that the industry puts people in this scenario in the pursuit of unfettered profit.

I just want to make sure you are aware that by choosing to use a unsupported device you are being exposed to significant threats to your device and your person by extension. With an device that’s been unsupported for as long as yours, it can be trivial for a malicious payload to infect your phone with malware.

Something as simple as visiting a website or even a text message can sometimes be enough to harm you. If you wish to continue using your device it may be wise to purge it of anything sensitive like access to your banking, photos, email, important accounts. I'm not trying to tell you how to use your phone and its very possible you're well aware of all this already.

There are privacy conscious projects out there with the idea of giving you control over the device you own. I'm not aware if this specific example I'm providing is compatible but it is a demonstration of what’s available. https://en.wikipedia.org/wiki//e/_(operating_system) Something like this won't necessarily solve all your issues (and could cause more like your s-pen comment), but it may help mitigate the low hanging fruit).