There are so many to choose from it can be daunting, I agree. But remember this: Firearms aren't like wives - you can have more than one at any given time and there's nothing wrong with that. ;)
Today's oils are better than they ever have been; and they work harder than they ever have in the past with VVT & forced induction becoming mainstream.
I'm in the change it often camp.
Look underneath for an identification sticker on the axles. If they're Dexter axles, you can go to their website & download the owners manual. My two trailers have Dexter axles, and JT6 is an approved grease by name.
Dexter
From the pic, looks like yours is the 2019 K2 flavor, not the 2019 T1xx (I have the '19 K2, myself). There's no inherent problems with those t-cases. And there hasn't been a manual shift option for quite some time, at least not from GM.
I see from your year-old other thread fluid changes on...
I assume this is a carry-on piece. Worse comes to worst, they'll just check it & throw it in the belly of the plane. Disclaimer - I've never flown international, only domestic.