I'm in a rare bizarre situation and this is a desperate attempt to not buy any new hardware.
Basically, I need a minimalist, no BS, no autoupdate, no auto-turn-back-bad-settings-weekly version of windows specifically for the purpose of running windows occasionally and only connecting my phone to it to run this one specific application https://www.samsung.com/uk/apps/samsung-dex/
Scrcpy does not trigger Samsung Dex (or Android Desktop for non-Samsung devices), otherwise I'd just use that on my Garuda MATE Linux installation. I will be tinking with wine later but I doubt it will work.
Any option that involves spending money will probably not be worth it because if I am spending money on this, I'd rather get a portable monitor (they're not that expensive).
Know of any specifically good windows ISO or what the gold standard of keeping a rogue OS like windows in check?
Windows 10 LTSC. It's made exactly for this.
Great choice. If you go specifically with the IoT LTSC version you’re also supported until 2032
Seconded, I didn't realize how bad Win 10 has gotten because I've used LTSC since Win 7. A far more bearable experience.