You should probably get a big ass micro SD card since they are pretty cheap these days. Not sure size limit since don't have a switch. Also if you are going to play mainly docked then you prob should get pro controller.
in terms of size limits I believe the Switch has a limit of 3TB micro SD card, but since the 1TB type of them has just launched this year and that costs 400 sterling, it will be a while before we are worrying about the Switches upper limits on SD card compatibility.
Fancy hearing me on an amateur podcast with friends gushing over one of my favourite games? https://youtu.be/1I7JfMMxhf8