I want to buy a Kittel, however many of them are linen. My Talis is wool and I would need to wear both at the same time. Does that constitute Shatnez?

This isn’t an issue since they can each be removed without the other.

 

Sources:

.ראה רמ״א יו״ד ש, ד. ובנו״כ שם. שו״ת שבה״ל ט, רכו. וראה דרך אמונה כלאים יו״ד