Welcome @gibsonriver2 and Ingo!

My sites for desktop and laptop are 1100 px. I find that 1100 also provides optimal tablet viewing in landscape and portrait. My mobile is the suggested Xara 750, but I’ve seen some sites for mobile that are 600 px.
I think the Xara suggested site settings for laptop and desktop are safe sizes for most consumer monitors. 1250px might be stretching for most at home monitors. I have a very large monitor but I do photo production as well

Nowadays my prime concern is mobile and tablet. The mobile viewing stats are very high.

Font sizes for myself are 12-14 px for desktop and tablet. 16-18 px mobile.

In regard to your viewing ratios that’s above my pay grade but many will chime in.

Hope that sheds a little light.

-Bill