This is what I use and it works well: 128G SanDisk USB stick. Can't remember if I had to reformat as FAT32, or if it came as FAT32 (the Nav manual does say only FAT16/32 are supported, but only FAT32 supports the large size you need). I have a 2023 LC, don't know if anything changed since earlier models.
https://www.amazon.co.uk/gp/product/B07855LJ99