I am downloading Mint xfce currently, was to see how that runs and if it goes well do cinnamon. The laptop has an M.2 SSD, unsure of the capacity, but I am going to guess 512gb.
I am 250ish, the majority I saw were 265 weight limit. I carry a rather heavy backpack, so even without the dog in the equation I would want something around 300.
I ordered a k1 max from keychron today. It was a bit more than I wanted to pay, but it looks to be a good board. This one looks interesting. I have used ergo boards but never a split board.
I have the k480 which I like for typing and such, but for gaming I find it too small. It looks to be similar to your 380 but the 480 has a slot to hold a tablet or phone.
I do like hearing the 380 has a case though.
I was looking at the Logitech mx keys s, but it is $130. At that point I would probably go with a gaming keyboard.
Or something like a grease gun that screws or clamps onto the valve and then forces the goop in.