"Is it weird to have white window inside original red oak trim?"

No, white windows are trimmed quite often with stained wood. But I doubt those are oak but tough to tell from the picture as it is dark.

Really appreciate reply. Plan to post better pix later today. Gotta decide this weekend!

It really comes down to personal preference. If you go with a vinyl you are limited on colors and if they dont match if does not look good. If you with a wood window there are also limeted stock colors or you can do a custom stain.

I am going with vinyl (affordablw). Here are more pix millworkman

There are some vinyl laminates that would match that pretty close. Not all vinyl manufactures have the same color though. I would expect to pay around an $80 minimum upcharge over basic white for this.

I have one that is a little close (when I stand 10 feet away I don't notice it). I think part of this question is also would white Sash "modernize" my wood trim home OR look out of place?

And even thought I'm "10 feet away" I know it doesn't "match" -- so that feels a bit off too

Here's a pix of white vs the sample on existing wood

I not fond of that woodgrain and not usually fond of the brands that use it. These are a few pics of woodgrains that other brands use that may work.