What are the must-have accessories for a Canon EOS R5?

So I finally pulled the trigger on the R5 after saving up for what feels like a decade. Im taking it to Iceland in about three weeks for a dream photography trip and honestly the price tag of the body alone almost killed me. Im mostly doing landscapes and hopefully some puffins or arctic foxes if I get lucky but now I am staring at my empty bag realizing I need the actual stuff to make it work. I have about 1500 left in the budget for accessories which sounds like a lot but then I started looking at CFexpress Type B cards and holy cow they are pricey. I saw some people online saying you HAVE to get the ProGrade Cobalt ones for the high bitrate video or fast bursts but then others say the cheaper ones like Lexar are fine if you arent shooting 8K? I dont plan on doing tons of video but I dont want to bottleneck the camera either especially with the file sizes this thing puts out.

Then there is the whole battery situation. I keep reading that the R5 eats through the LP-E6NH batteries like crazy so I was looking at the BG-R10 battery grip. Some forums say it makes the ergonomics way better for vertical shots but others complain it makes the camera too heavy for hiking which is basically all I will be doing in the highlands. If I skip the grip should I just buy like four extra batteries? Also I am super paranoid about the weather over there so I was looking at those Peak Design covers or maybe just a really good L-bracket. I already have a decent tripod but I feel like I am missing something obvious that every R5 owner knows about because this is a big jump for me from my old DSLR.

If you guys were setting up an R5 from scratch for a big nature trip what would be on your absolute must-have list? Is the grip a trap for hikers? What cards are you actually using day to day without issues...