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?
Atlas is my favorite version. Even LTT did a video about it. You just install a normal Windows 10 or 11 iso then run the atlas installer and it does a pretty good job making Windows minimal bullshit by replacing edge with Firefox, disabling countless anti features, and installing openshell.
If it's just for that one purpose have you considered running windows in a VM and passing though that one usb device? Gnome boxes makes that pretty easy.