When I took a screenshot on the Minimal and emailed it to myself (to view on my laptop), the screenshot was in color.
Just tested this, the colour correction only affects the displayed image on my device, not screenshots
Either I don't have that option or it's buried under a different name/menu path.
Not sure when the ability to add custom mode was added (I'm on android 16), but it's part of the menu that contains bedtime mode, driving mode and DND (edit: custom modes were added in one of the android 15 updates). You could use one of those preset modes and set the display setting for it to grey scale, but I've noticed that colour correction actually has a quick settings toggle, so you could use that with colour correction set to grey scale as a sort of reading mode as well. Here's what my modes menu looks like on my phone:
I've double-checked because I'm not familiar with Microsoft licensing terminology. The extended support end period listed is included without extra cost, it's just limited to security updates only. This is separate from "Extended Security Updates" which is paid for security updates after the support period has ended.
"The Extended Support phase follows Mainstream Support. At the supported service pack level, Extended Support includes [...] Security updates at no additional cost"